feat(csharp) .NET 8.0 code migration (#966)

* .net 8.0 migration

* update docs

* revert change

* revert change and update appendix docs

* remove static

* Update binary_search_insertion.cs

* Update binary_search_insertion.cs

* Update binary_search_edge.cs

* Update binary_search_insertion.cs

* Update binary_search_edge.cs

---------

Co-authored-by: Yudong Jin <krahets@163.com>

.github/workflows/dotnet.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        dotnet-version: ["6.0.x"]
+        dotnet-version: ["8.0.x"]
 
     steps:
     - uses: actions/checkout@v4

codes/Dockerfile

@@ -22,7 +22,7 @@ RUN for LANG in $LANGS; do \
                 wget https://packages.microsoft.com/config/ubuntu/20.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb && \
                 dpkg -i packages-microsoft-prod.deb && \
                 apt-get update && \
-                apt-get install -y dotnet-sdk-6.0 ;; \
+                apt-get install -y dotnet-sdk-8.0 ;; \
             # More languages...
             *) \
                 echo "Warning: No installation workflow for $LANG" ;; \

codes/csharp/.editorconfig

@@ -4,3 +4,85 @@ csharp_new_line_before_open_brace = none
 csharp_new_line_before_else = false
 csharp_new_line_before_catch = false
 csharp_new_line_before_finally = false
+csharp_indent_labels = one_less_than_current
+csharp_using_directive_placement = outside_namespace:silent
+csharp_prefer_simple_using_statement = true:suggestion
+csharp_prefer_braces = true:silent
+csharp_style_namespace_declarations = block_scoped:silent
+csharp_style_prefer_method_group_conversion = true:silent
+csharp_style_prefer_top_level_statements = true:silent
+csharp_style_prefer_primary_constructors = true:suggestion
+csharp_style_expression_bodied_methods = false:silent
+csharp_style_expression_bodied_constructors = false:silent
+csharp_style_expression_bodied_operators = false:silent
+csharp_style_expression_bodied_properties = true:silent
+csharp_style_expression_bodied_indexers = true:silent
+csharp_style_expression_bodied_accessors = true:silent
+csharp_style_expression_bodied_lambdas = true:silent
+
+# CS8981: The type name only contains lower-cased ascii characters. Such names may become reserved for the language.
+dotnet_diagnostic.CS8981.severity = silent
+
+# IDE1006: Naming Styles
+dotnet_diagnostic.IDE1006.severity = silent
+
+# CA1822: Mark members as static
+dotnet_diagnostic.CA1822.severity = silent
+
+[*.{cs,vb}]
+#### Naming styles ####
+
+# Naming rules
+
+dotnet_naming_rule.interface_should_be_begins_with_i.severity = suggestion
+dotnet_naming_rule.interface_should_be_begins_with_i.symbols = interface
+dotnet_naming_rule.interface_should_be_begins_with_i.style = begins_with_i
+
+dotnet_naming_rule.types_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.types_should_be_pascal_case.symbols = types
+dotnet_naming_rule.types_should_be_pascal_case.style = pascal_case
+
+dotnet_naming_rule.non_field_members_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.non_field_members_should_be_pascal_case.symbols = non_field_members
+dotnet_naming_rule.non_field_members_should_be_pascal_case.style = pascal_case
+
+# Symbol specifications
+
+dotnet_naming_symbols.interface.applicable_kinds = interface
+dotnet_naming_symbols.interface.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.interface.required_modifiers = 
+
+dotnet_naming_symbols.types.applicable_kinds = class, struct, interface, enum
+dotnet_naming_symbols.types.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.types.required_modifiers = 
+
+dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
+dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.non_field_members.required_modifiers = 
+
+# Naming styles
+
+dotnet_naming_style.begins_with_i.required_prefix = I
+dotnet_naming_style.begins_with_i.required_suffix = 
+dotnet_naming_style.begins_with_i.word_separator = 
+dotnet_naming_style.begins_with_i.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+dotnet_style_operator_placement_when_wrapping = beginning_of_line
+tab_width = 4
+indent_size = 4
+end_of_line = crlf
+
+# IDE0040: Add accessibility modifiers
+dotnet_diagnostic.IDE0040.severity = silent
+
+# IDE0044: Add readonly modifier
+dotnet_diagnostic.IDE0044.severity = silent

codes/csharp/chapter_array_and_linkedlist/array.cs

@@ -6,7 +6,7 @@ namespace hello_algo.chapter_array_and_linkedlist;
 
 public class array {
     /* 随机访问元素 */
-    public static int RandomAccess(int[] nums) {
+    int RandomAccess(int[] nums) {
         Random random = new();
         // 在区间 [0, nums.Length) 中随机抽取一个数字
         int randomIndex = random.Next(nums.Length);
@@ -16,7 +16,7 @@ public class array {
     }
 
     /* 扩展数组长度 */
-    public static int[] Extend(int[] nums, int enlarge) {
+    int[] Extend(int[] nums, int enlarge) {
         // 初始化一个扩展长度后的数组
         int[] res = new int[nums.Length + enlarge];
         // 将原数组中的所有元素复制到新数组
@@ -28,7 +28,7 @@ public class array {
     }
 
     /* 在数组的索引 index 处插入元素 num */
-    public static void Insert(int[] nums, int num, int index) {
+    void Insert(int[] nums, int num, int index) {
         // 把索引 index 以及之后的所有元素向后移动一位
         for (int i = nums.Length - 1; i > index; i--) {
             nums[i] = nums[i - 1];
@@ -38,7 +38,7 @@ public class array {
     }
 
     /* 删除索引 index 处元素 */
-    public static void Remove(int[] nums, int index) {
+    void Remove(int[] nums, int index) {
         // 把索引 index 之后的所有元素向前移动一位
         for (int i = index; i < nums.Length - 1; i++) {
             nums[i] = nums[i + 1];
@@ -46,7 +46,7 @@ public class array {
     }
 
     /* 遍历数组 */
-    public static void Traverse(int[] nums) {
+    void Traverse(int[] nums) {
         int count = 0;
         // 通过索引遍历数组
         for (int i = 0; i < nums.Length; i++) {
@@ -59,7 +59,7 @@ public class array {
     }
 
     /* 在数组中查找指定元素 */
-    public static int Find(int[] nums, int target) {
+    int Find(int[] nums, int target) {
         for (int i = 0; i < nums.Length; i++) {
             if (nums[i] == target)
                 return i;
@@ -68,17 +68,17 @@ public class array {
     }
 
     /* 辅助函数,数组转字符串 */
-    public static string ToString(int[] nums) {
+    string ToString(int[] nums) {
         return string.Join(",", nums);
     }
 
 
     [Test]
-    public static void Test() {
+    public void Test() {
         // 初始化数组
         int[] arr = new int[5];
         Console.WriteLine("数组 arr = " + ToString(arr));
-        int[] nums = { 1, 3, 2, 5, 4 };
+        int[] nums = [1, 3, 2, 5, 4];
         Console.WriteLine("数组 nums = " + ToString(nums));
 
         // 随机访问

codes/csharp/chapter_array_and_linkedlist/linked_list.cs

@@ -6,14 +6,14 @@ namespace hello_algo.chapter_array_and_linkedlist;
 
 public class linked_list {
     /* 在链表的节点 n0 之后插入节点 P */
-    public static void Insert(ListNode n0, ListNode P) {
+    void Insert(ListNode n0, ListNode P) {
         ListNode? n1 = n0.next;
         P.next = n1;
         n0.next = P;
     }
 
     /* 删除链表的节点 n0 之后的首个节点 */
-    public static void Remove(ListNode n0) {
+    void Remove(ListNode n0) {
         if (n0.next == null)
             return;
         // n0 -> P -> n1
@@ -23,7 +23,7 @@ public class linked_list {
     }
 
     /* 访问链表中索引为 index 的节点 */
-    public static ListNode? Access(ListNode head, int index) {
+    ListNode? Access(ListNode? head, int index) {
         for (int i = 0; i < index; i++) {
             if (head == null)
                 return null;
@@ -33,7 +33,7 @@ public class linked_list {
     }
 
     /* 在链表中查找值为 target 的首个节点 */
-    public static int Find(ListNode head, int target) {
+    int Find(ListNode? head, int target) {
         int index = 0;
         while (head != null) {
             if (head.val == target)

codes/csharp/chapter_array_and_linkedlist/list.cs

@@ -11,8 +11,8 @@ public class list {
     public void Test() {
 
         /* 初始化列表 */
-        int[] numbers = new int[] { 1, 3, 2, 5, 4 };
+        int[] numbers = [1, 3, 2, 5, 4];
-        List<int> nums = numbers.ToList();
+        List<int> nums = [.. numbers];
         Console.WriteLine("列表 nums = " + string.Join(",", nums));
 
         /* 访问元素 */
@@ -55,7 +55,7 @@ public class list {
         }
 
         /* 拼接两个列表 */
-        List<int> nums1 = new() { 6, 8, 7, 10, 9 };
+        List<int> nums1 = [6, 8, 7, 10, 9];
         nums.AddRange(nums1);
         Console.WriteLine("将列表 nums1 拼接到 nums 之后，得到 nums = " + string.Join(",", nums));
 

codes/csharp/chapter_backtracking/n_queens.cs

@@ -8,11 +8,11 @@ namespace hello_algo.chapter_backtracking;
 
 public class n_queens {
     /* 回溯算法：N 皇后 */
-    static void Backtrack(int row, int n, List<List<string>> state, List<List<List<string>>> res,
+    void Backtrack(int row, int n, List<List<string>> state, List<List<List<string>>> res,
             bool[] cols, bool[] diags1, bool[] diags2) {
         // 当放置完所有行时，记录解
         if (row == n) {
-            List<List<string>> copyState = new();
+            List<List<string>> copyState = [];
             foreach (List<string> sRow in state) {
                 copyState.Add(new List<string>(sRow));
             }
@@ -39,11 +39,11 @@ public class n_queens {
     }
 
     /* 求解 N 皇后 */
-    static List<List<List<string>>> NQueens(int n) {
+    List<List<List<string>>> NQueens(int n) {
         // 初始化 n*n 大小的棋盘，其中 'Q' 代表皇后，'#' 代表空位
-        List<List<string>> state = new();
+        List<List<string>> state = [];
         for (int i = 0; i < n; i++) {
-            List<string> row = new();
+            List<string> row = [];
             for (int j = 0; j < n; j++) {
                 row.Add("#");
             }
@@ -52,7 +52,7 @@ public class n_queens {
         bool[] cols = new bool[n]; // 记录列是否有皇后
         bool[] diags1 = new bool[2 * n - 1]; // 记录主对角线是否有皇后
         bool[] diags2 = new bool[2 * n - 1]; // 记录副对角线是否有皇后
-        List<List<List<string>>> res = new();
+        List<List<List<string>>> res = [];
 
         Backtrack(0, n, state, res, cols, diags1, diags2);
 

codes/csharp/chapter_backtracking/permutations_i.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_backtracking;
 
 public class permutations_i {
     /* 回溯算法：全排列 I */
-    static void Backtrack(List<int> state, int[] choices, bool[] selected, List<List<int>> res) {
+    void Backtrack(List<int> state, int[] choices, bool[] selected, List<List<int>> res) {
         // 当状态长度等于元素数量时，记录解
         if (state.Count == choices.Length) {
             res.Add(new List<int>(state));
@@ -32,15 +32,15 @@ public class permutations_i {
     }
 
     /* 全排列 I */
-    static List<List<int>> PermutationsI(int[] nums) {
+    List<List<int>> PermutationsI(int[] nums) {
-        List<List<int>> res = new();
+        List<List<int>> res = [];
-        Backtrack(new List<int>(), nums, new bool[nums.Length], res);
+        Backtrack([], nums, new bool[nums.Length], res);
         return res;
     }
 
     [Test]
     public void Test() {
-        int[] nums = { 1, 2, 3 };
+        int[] nums = [1, 2, 3];
 
         List<List<int>> res = PermutationsI(nums);
 

codes/csharp/chapter_backtracking/permutations_ii.cs

@@ -8,14 +8,14 @@ namespace hello_algo.chapter_backtracking;
 
 public class permutations_ii {
     /* 回溯算法：全排列 II */
-    static void Backtrack(List<int> state, int[] choices, bool[] selected, List<List<int>> res) {
+    void Backtrack(List<int> state, int[] choices, bool[] selected, List<List<int>> res) {
         // 当状态长度等于元素数量时，记录解
         if (state.Count == choices.Length) {
             res.Add(new List<int>(state));
             return;
         }
         // 遍历所有选择
-        ISet<int> duplicated = new HashSet<int>();
+        HashSet<int> duplicated = [];
         for (int i = 0; i < choices.Length; i++) {
             int choice = choices[i];
             // 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
@@ -34,15 +34,15 @@ public class permutations_ii {
     }
 
     /* 全排列 II */
-    static List<List<int>> PermutationsII(int[] nums) {
+    List<List<int>> PermutationsII(int[] nums) {
-        List<List<int>> res = new();
+        List<List<int>> res = [];
-        Backtrack(new List<int>(), nums, new bool[nums.Length], res);
+        Backtrack([], nums, new bool[nums.Length], res);
         return res;
     }
 
     [Test]
     public void Test() {
-        int[] nums = { 1, 2, 2 };
+        int[] nums = [1, 2, 2];
 
         List<List<int>> res = PermutationsII(nums);
 

codes/csharp/chapter_backtracking/preorder_traversal_i_compact.cs

@@ -7,10 +7,10 @@
 namespace hello_algo.chapter_backtracking;
 
 public class preorder_traversal_i_compact {
-    static List<TreeNode> res;
+    List<TreeNode> res = [];
 
     /* 前序遍历：例题一 */
-    static void PreOrder(TreeNode root) {
+    void PreOrder(TreeNode? root) {
         if (root == null) {
             return;
         }
@@ -24,12 +24,11 @@ public class preorder_traversal_i_compact {
 
     [Test]
     public void Test() {
-        TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 7, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树");
         PrintUtil.PrintTree(root);
 
         // 前序遍历
-        res = new List<TreeNode>();
         PreOrder(root);
 
         Console.WriteLine("\n输出所有值为 7 的节点");

codes/csharp/chapter_backtracking/preorder_traversal_ii_compact.cs

@@ -7,11 +7,11 @@
 namespace hello_algo.chapter_backtracking;
 
 public class preorder_traversal_ii_compact {
-    static List<TreeNode> path;
+    List<TreeNode> path = [];
-    static List<List<TreeNode>> res;
+    List<List<TreeNode>> res = [];
 
     /* 前序遍历：例题二 */
-    static void PreOrder(TreeNode root) {
+    void PreOrder(TreeNode? root) {
         if (root == null) {
             return;
         }
@@ -29,13 +29,11 @@ public class preorder_traversal_ii_compact {
 
     [Test]
     public void Test() {
-        TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 7, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树");
         PrintUtil.PrintTree(root);
 
         // 前序遍历
-        path = new List<TreeNode>();
-        res = new List<List<TreeNode>>();
         PreOrder(root);
 
         Console.WriteLine("\n输出所有根节点到节点 7 的路径");

codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs

@@ -7,11 +7,11 @@
 namespace hello_algo.chapter_backtracking;
 
 public class preorder_traversal_iii_compact {
-    static List<TreeNode> path;
+    List<TreeNode> path = [];
-    static List<List<TreeNode>> res;
+    List<List<TreeNode>> res = [];
 
     /* 前序遍历：例题三 */
-    static void PreOrder(TreeNode root) {
+    void PreOrder(TreeNode? root) {
         // 剪枝
         if (root == null || root.val == 3) {
             return;
@@ -30,13 +30,11 @@ public class preorder_traversal_iii_compact {
 
     [Test]
     public void Test() {
-        TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 7, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树");
         PrintUtil.PrintTree(root);
 
         // 前序遍历
-        path = new List<TreeNode>();
-        res = new List<List<TreeNode>>();
         PreOrder(root);
 
         Console.WriteLine("\n输出所有根节点到节点 7 的路径，路径中不包含值为 3 的节点");

codes/csharp/chapter_backtracking/preorder_traversal_iii_template.cs

@@ -8,32 +8,32 @@ namespace hello_algo.chapter_backtracking;
 
 public class preorder_traversal_iii_template {
     /* 判断当前状态是否为解 */
-    static bool IsSolution(List<TreeNode> state) {
+    bool IsSolution(List<TreeNode> state) {
         return state.Count != 0 && state[^1].val == 7;
     }
 
     /* 记录解 */
-    static void RecordSolution(List<TreeNode> state, List<List<TreeNode>> res) {
+    void RecordSolution(List<TreeNode> state, List<List<TreeNode>> res) {
         res.Add(new List<TreeNode>(state));
     }
 
     /* 判断在当前状态下，该选择是否合法 */
-    static bool IsValid(List<TreeNode> state, TreeNode choice) {
+    bool IsValid(List<TreeNode> state, TreeNode choice) {
         return choice != null && choice.val != 3;
     }
 
     /* 更新状态 */
-    static void MakeChoice(List<TreeNode> state, TreeNode choice) {
+    void MakeChoice(List<TreeNode> state, TreeNode choice) {
         state.Add(choice);
     }
 
     /* 恢复状态 */
-    static void UndoChoice(List<TreeNode> state, TreeNode choice) {
+    void UndoChoice(List<TreeNode> state, TreeNode choice) {
         state.RemoveAt(state.Count - 1);
     }
 
     /* 回溯算法：例题三 */
-    static void Backtrack(List<TreeNode> state, List<TreeNode> choices, List<List<TreeNode>> res) {
+    void Backtrack(List<TreeNode> state, List<TreeNode> choices, List<List<TreeNode>> res) {
         // 检查是否为解
         if (IsSolution(state)) {
             // 记录解
@@ -46,7 +46,7 @@ public class preorder_traversal_iii_template {
                 // 尝试：做出选择，更新状态
                 MakeChoice(state, choice);
                 // 进行下一轮选择
-                Backtrack(state, new List<TreeNode> { choice.left, choice.right }, res);
+                Backtrack(state, [choice.left!, choice.right!], res);
                 // 回退：撤销选择，恢复到之前的状态
                 UndoChoice(state, choice);
             }
@@ -55,14 +55,14 @@ public class preorder_traversal_iii_template {
 
     [Test]
     public void Test() {
-        TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 7, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树");
         PrintUtil.PrintTree(root);
 
         // 回溯算法
-        List<List<TreeNode>> res = new();
+        List<List<TreeNode>> res = [];
-        List<TreeNode> choices = new() { root };
+        List<TreeNode> choices = [root!];
-        Backtrack(new List<TreeNode>(), choices, res);
+        Backtrack([], choices, res);
 
         Console.WriteLine("\n输出所有根节点到节点 7 的路径，要求路径中不包含值为 3 的节点");
         foreach (List<TreeNode> path in res) {

codes/csharp/chapter_backtracking/subset_sum_i.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_backtracking;
 
 public class subset_sum_i {
     /* 回溯算法：子集和 I */
-    public static void Backtrack(List<int> state, int target, int[] choices, int start, List<List<int>> res) {
+    void Backtrack(List<int> state, int target, int[] choices, int start, List<List<int>> res) {
         // 子集和等于 target 时，记录解
         if (target == 0) {
             res.Add(new List<int>(state));
@@ -32,18 +32,18 @@ public class subset_sum_i {
     }
 
     /* 求解子集和 I */
-    public static List<List<int>> SubsetSumI(int[] nums, int target) {
+    List<List<int>> SubsetSumI(int[] nums, int target) {
-        List<int> state = new(); // 状态（子集）
+        List<int> state = []; // 状态（子集）
         Array.Sort(nums); // 对 nums 进行排序
         int start = 0; // 遍历起始点
-        List<List<int>> res = new(); // 结果列表（子集列表）
+        List<List<int>> res = []; // 结果列表（子集列表）
         Backtrack(state, target, nums, start, res);
         return res;
     }
 
     [Test]
     public void Test() {
-        int[] nums = { 3, 4, 5 };
+        int[] nums = [3, 4, 5];
         int target = 9;
         List<List<int>> res = SubsetSumI(nums, target);
         Console.WriteLine("输入数组 nums = " + string.Join(", ", nums) + ", target = " + target);

codes/csharp/chapter_backtracking/subset_sum_i_naive.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_backtracking;
 
 public class subset_sum_i_naive {
     /* 回溯算法：子集和 I */
-    public static void Backtrack(List<int> state, int target, int total, int[] choices, List<List<int>> res) {
+    void Backtrack(List<int> state, int target, int total, int[] choices, List<List<int>> res) {
         // 子集和等于 target 时，记录解
         if (total == target) {
             res.Add(new List<int>(state));
@@ -30,17 +30,17 @@ public class subset_sum_i_naive {
     }
 
     /* 求解子集和 I（包含重复子集） */
-    public static List<List<int>> SubsetSumINaive(int[] nums, int target) {
+    List<List<int>> SubsetSumINaive(int[] nums, int target) {
-        List<int> state = new(); // 状态（子集）
+        List<int> state = []; // 状态（子集）
         int total = 0; // 子集和
-        List<List<int>> res = new(); // 结果列表（子集列表）
+        List<List<int>> res = []; // 结果列表（子集列表）
         Backtrack(state, target, total, nums, res);
         return res;
     }
 
     [Test]
     public void Test() {
-        int[] nums = { 3, 4, 5 };
+        int[] nums = [3, 4, 5];
         int target = 9;
         List<List<int>> res = SubsetSumINaive(nums, target);
         Console.WriteLine("输入数组 nums = " + string.Join(", ", nums) + ", target = " + target);

codes/csharp/chapter_backtracking/subset_sum_ii.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_backtracking;
 
 public class subset_sum_ii {
     /* 回溯算法：子集和 II */
-    public static void Backtrack(List<int> state, int target, int[] choices, int start, List<List<int>> res) {
+    void Backtrack(List<int> state, int target, int[] choices, int start, List<List<int>> res) {
         // 子集和等于 target 时，记录解
         if (target == 0) {
             res.Add(new List<int>(state));
@@ -37,18 +37,18 @@ public class subset_sum_ii {
     }
 
     /* 求解子集和 II */
-    public static List<List<int>> SubsetSumII(int[] nums, int target) {
+    List<List<int>> SubsetSumII(int[] nums, int target) {
-        List<int> state = new(); // 状态（子集）
+        List<int> state = []; // 状态（子集）
         Array.Sort(nums); // 对 nums 进行排序
         int start = 0; // 遍历起始点
-        List<List<int>> res = new(); // 结果列表（子集列表）
+        List<List<int>> res = []; // 结果列表（子集列表）
         Backtrack(state, target, nums, start, res);
         return res;
     }
 
     [Test]
     public void Test() {
-        int[] nums = { 4, 4, 5 };
+        int[] nums = [4, 4, 5];
         int target = 9;
         List<List<int>> res = SubsetSumII(nums, target);
         Console.WriteLine("输入数组 nums = " + string.Join(", ", nums) + ", target = " + target);

codes/csharp/chapter_computational_complexity/iteration.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_computational_complexity;
 
 public class iteration {
     /* for 循环 */
-    public static int ForLoop(int n) {
+    int ForLoop(int n) {
         int res = 0;
         // 循环求和 1, 2, ..., n-1, n
         for (int i = 1; i <= n; i++) {
@@ -18,7 +18,7 @@ public class iteration {
     }
 
     /* while 循环 */
-    public static int WhileLoop(int n) {
+    int WhileLoop(int n) {
         int res = 0;
         int i = 1; // 初始化条件变量
         // 循环求和 1, 2, ..., n-1, n
@@ -30,7 +30,7 @@ public class iteration {
     }
 
     /* while 循环（两次更新） */
-    public static int WhileLoopII(int n) {
+    int WhileLoopII(int n) {
         int res = 0;
         int i = 1; // 初始化条件变量
         // 循环求和 1, 2, 4, 5...
@@ -44,7 +44,7 @@ public class iteration {
     }
 
     /* 双层 for 循环 */
-    public static string NestedForLoop(int n) {
+    string NestedForLoop(int n) {
         StringBuilder res = new();
         // 循环 i = 1, 2, ..., n-1, n
         for (int i = 1; i <= n; i++) {

codes/csharp/chapter_computational_complexity/recursion.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_computational_complexity;
 
 public class recursion {
     /* 递归 */
-    public int Recur(int n) {
+    int Recur(int n) {
         // 终止条件
         if (n == 1)
             return 1;
@@ -19,7 +19,7 @@ public class recursion {
     }
 
     /* 使用迭代模拟递归 */
-    public static int ForLoopRecur(int n) {
+    int ForLoopRecur(int n) {
         // 使用一个显式的栈来模拟系统调用栈
         Stack<int> stack = new();
         int res = 0;
@@ -38,7 +38,7 @@ public class recursion {
     }
 
     /* 尾递归 */
-    public int TailRecur(int n, int res) {
+    int TailRecur(int n, int res) {
         // 终止条件
         if (n == 0)
             return res;
@@ -47,7 +47,7 @@ public class recursion {
     }
 
     /* 斐波那契数列：递归 */
-    public int Fib(int n) {
+    int Fib(int n) {
         // 终止条件 f(1) = 0, f(2) = 1
         if (n == 1 || n == 2)
             return n - 1;

codes/csharp/chapter_computational_complexity/space_complexity.cs

@@ -8,13 +8,13 @@ namespace hello_algo.chapter_computational_complexity;
 
 public class space_complexity {
     /* 函数 */
-    static int Function() {
+    int Function() {
         // 执行某些操作
         return 0;
     }
 
     /* 常数阶 */
-    static void Constant(int n) {
+    void Constant(int n) {
         // 常量、变量、对象占用 O(1) 空间
         int a = 0;
         int b = 0;
@@ -31,36 +31,36 @@ public class space_complexity {
     }
 
     /* 线性阶 */
-    static void Linear(int n) {
+    void Linear(int n) {
         // 长度为 n 的数组占用 O(n) 空间
         int[] nums = new int[n];
         // 长度为 n 的列表占用 O(n) 空间
-        List<ListNode> nodes = new();
+        List<ListNode> nodes = [];
         for (int i = 0; i < n; i++) {
             nodes.Add(new ListNode(i));
         }
         // 长度为 n 的哈希表占用 O(n) 空间
-        Dictionary<int, string> map = new();
+        Dictionary<int, string> map = [];
         for (int i = 0; i < n; i++) {
             map.Add(i, i.ToString());
         }
     }
 
     /* 线性阶（递归实现） */
-    static void LinearRecur(int n) {
+    void LinearRecur(int n) {
         Console.WriteLine("递归 n = " + n);
         if (n == 1) return;
         LinearRecur(n - 1);
     }
 
     /* 平方阶 */
-    static void Quadratic(int n) {
+    void Quadratic(int n) {
         // 矩阵占用 O(n^2) 空间
         int[,] numMatrix = new int[n, n];
         // 二维列表占用 O(n^2) 空间
-        List<List<int>> numList = new();
+        List<List<int>> numList = [];
         for (int i = 0; i < n; i++) {
-            List<int> tmp = new();
+            List<int> tmp = [];
             for (int j = 0; j < n; j++) {
                 tmp.Add(0);
             }
@@ -69,7 +69,7 @@ public class space_complexity {
     }
 
     /* 平方阶（递归实现） */
-    static int QuadraticRecur(int n) {
+    int QuadraticRecur(int n) {
         if (n <= 0) return 0;
         int[] nums = new int[n];
         Console.WriteLine("递归 n = " + n + " 中的 nums 长度 = " + nums.Length);
@@ -77,7 +77,7 @@ public class space_complexity {
     }
 
     /* 指数阶（建立满二叉树） */
-    static TreeNode? BuildTree(int n) {
+    TreeNode? BuildTree(int n) {
         if (n == 0) return null;
         TreeNode root = new(0) {
             left = BuildTree(n - 1),

codes/csharp/chapter_computational_complexity/time_complexity.cs

@@ -9,7 +9,7 @@ namespace hello_algo.chapter_computational_complexity;
 public class time_complexity {
     void Algorithm(int n) {
         int a = 1;  // +0（技巧 1）
-        a = a + n;  // +0（技巧 1）
+        a += n;  // +0（技巧 1）
                     // +n（技巧 2）
         for (int i = 0; i < 5 * n + 1; i++) {
             Console.WriteLine(0);
@@ -26,12 +26,14 @@ public class time_complexity {
     void AlgorithmA(int n) {
         Console.WriteLine(0);
     }
+
     // 算法 B 时间复杂度：线性阶
     void AlgorithmB(int n) {
         for (int i = 0; i < n; i++) {
             Console.WriteLine(0);
         }
     }
+
     // 算法 C 时间复杂度：常数阶
     void AlgorithmC(int n) {
         for (int i = 0; i < 1000000; i++) {
@@ -40,7 +42,7 @@ public class time_complexity {
     }
 
     /* 常数阶 */
-    static int Constant(int n) {
+    int Constant(int n) {
         int count = 0;
         int size = 100000;
         for (int i = 0; i < size; i++)
@@ -49,7 +51,7 @@ public class time_complexity {
     }
 
     /* 线性阶 */
-    static int Linear(int n) {
+    int Linear(int n) {
         int count = 0;
         for (int i = 0; i < n; i++)
             count++;
@@ -57,7 +59,7 @@ public class time_complexity {
     }
 
     /* 线性阶（遍历数组） */
-    static int ArrayTraversal(int[] nums) {
+    int ArrayTraversal(int[] nums) {
         int count = 0;
         // 循环次数与数组长度成正比
         foreach (int num in nums) {
@@ -67,7 +69,7 @@ public class time_complexity {
     }
 
     /* 平方阶 */
-    static int Quadratic(int n) {
+    int Quadratic(int n) {
         int count = 0;
         // 循环次数与数组长度成平方关系
         for (int i = 0; i < n; i++) {
@@ -79,7 +81,7 @@ public class time_complexity {
     }
 
     /* 平方阶（冒泡排序） */
-    static int BubbleSort(int[] nums) {
+    int BubbleSort(int[] nums) {
         int count = 0;  // 计数器
         // 外循环：未排序区间为 [0, i]
         for (int i = nums.Length - 1; i > 0; i--) {
@@ -96,7 +98,7 @@ public class time_complexity {
     }
 
     /* 指数阶（循环实现） */
-    static int Exponential(int n) {
+    int Exponential(int n) {
         int count = 0, bas = 1;
         // 细胞每轮一分为二，形成数列 1, 2, 4, 8, ..., 2^(n-1)
         for (int i = 0; i < n; i++) {
@@ -110,29 +112,29 @@ public class time_complexity {
     }
 
     /* 指数阶（递归实现） */
-    static int ExpRecur(int n) {
+    int ExpRecur(int n) {
         if (n == 1) return 1;
         return ExpRecur(n - 1) + ExpRecur(n - 1) + 1;
     }
 
     /* 对数阶（循环实现） */
-    static int Logarithmic(float n) {
+    int Logarithmic(float n) {
         int count = 0;
         while (n > 1) {
-            n = n / 2;
+            n /= 2;
             count++;
         }
         return count;
     }
 
     /* 对数阶（递归实现） */
-    static int LogRecur(float n) {
+    int LogRecur(float n) {
         if (n <= 1) return 0;
         return LogRecur(n / 2) + 1;
     }
 
     /* 线性对数阶 */
-    static int LinearLogRecur(float n) {
+    int LinearLogRecur(float n) {
         if (n <= 1) return 1;
         int count = LinearLogRecur(n / 2) + LinearLogRecur(n / 2);
         for (int i = 0; i < n; i++) {
@@ -142,7 +144,7 @@ public class time_complexity {
     }
 
     /* 阶乘阶（递归实现） */
-    static int FactorialRecur(int n) {
+    int FactorialRecur(int n) {
         if (n == 0) return 1;
         int count = 0;
         // 从 1 个分裂出 n 个

codes/csharp/chapter_computational_complexity/worst_best_time_complexity.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_computational_complexity;
 
 public class worst_best_time_complexity {
     /* 生成一个数组，元素为 { 1, 2, ..., n }，顺序被打乱 */
-    static int[] RandomNumbers(int n) {
+    int[] RandomNumbers(int n) {
         int[] nums = new int[n];
         // 生成数组 nums = { 1, 2, 3, ..., n }
         for (int i = 0; i < n; i++) {
@@ -24,7 +24,7 @@ public class worst_best_time_complexity {
     }
 
     /* 查找数组 nums 中数字 1 所在索引 */
-    static int FindOne(int[] nums) {
+    int FindOne(int[] nums) {
         for (int i = 0; i < nums.Length; i++) {
             // 当元素 1 在数组头部时，达到最佳时间复杂度 O(1)
             // 当元素 1 在数组尾部时，达到最差时间复杂度 O(n)

codes/csharp/chapter_divide_and_conquer/binary_search_recur.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_divide_and_conquer;
 
 public class binary_search_recur {
     /* 二分查找：问题 f(i, j) */
-    public int DFS(int[] nums, int target, int i, int j) {
+    int DFS(int[] nums, int target, int i, int j) {
         // 若区间为空，代表无目标元素，则返回 -1
         if (i > j) {
             return -1;
@@ -28,7 +28,7 @@ public class binary_search_recur {
     }
 
     /* 二分查找 */
-    public int BinarySearch(int[] nums, int target) {
+    int BinarySearch(int[] nums, int target) {
         int n = nums.Length;
         // 求解问题 f(0, n-1)
         return DFS(nums, target, 0, n - 1);
@@ -37,7 +37,7 @@ public class binary_search_recur {
     [Test]
     public void Test() {
         int target = 6;
-        int[] nums = { 1, 3, 6, 8, 12, 15, 23, 26, 31, 35 };
+        int[] nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
 
         // 二分查找（双闭区间）
         int index = BinarySearch(nums, target);

codes/csharp/chapter_divide_and_conquer/build_tree.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_divide_and_conquer;
 
 public class build_tree {
     /* 构建二叉树：分治 */
-    public TreeNode DFS(int[] preorder, Dictionary<int, int> inorderMap, int i, int l, int r) {
+    TreeNode? DFS(int[] preorder, Dictionary<int, int> inorderMap, int i, int l, int r) {
         // 子树区间为空时终止
         if (r - l < 0)
             return null;
@@ -25,24 +25,24 @@ public class build_tree {
     }
 
     /* 构建二叉树 */
-    public TreeNode BuildTree(int[] preorder, int[] inorder) {
+    TreeNode? BuildTree(int[] preorder, int[] inorder) {
         // 初始化哈希表，存储 inorder 元素到索引的映射
-        Dictionary<int, int> inorderMap = new();
+        Dictionary<int, int> inorderMap = [];
         for (int i = 0; i < inorder.Length; i++) {
             inorderMap.TryAdd(inorder[i], i);
         }
-        TreeNode root = DFS(preorder, inorderMap, 0, 0, inorder.Length - 1);
+        TreeNode? root = DFS(preorder, inorderMap, 0, 0, inorder.Length - 1);
         return root;
     }
 
     [Test]
     public void Test() {
-        int[] preorder = { 3, 9, 2, 1, 7 };
+        int[] preorder = [3, 9, 2, 1, 7];
-        int[] inorder = { 9, 3, 1, 2, 7 };
+        int[] inorder = [9, 3, 1, 2, 7];
         Console.WriteLine("前序遍历 = " + string.Join(", ", preorder));
         Console.WriteLine("中序遍历 = " + string.Join(", ", inorder));
 
-        TreeNode root = BuildTree(preorder, inorder);
+        TreeNode? root = BuildTree(preorder, inorder);
         Console.WriteLine("构建的二叉树为：");
         PrintUtil.PrintTree(root);
     }

codes/csharp/chapter_divide_and_conquer/hanota.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_divide_and_conquer;
 
 public class hanota {
     /* 移动一个圆盘 */
-    public void Move(List<int> src, List<int> tar) {
+    void Move(List<int> src, List<int> tar) {
         // 从 src 顶部拿出一个圆盘
         int pan = src[^1];
         src.RemoveAt(src.Count - 1);
@@ -17,7 +17,7 @@ public class hanota {
     }
 
     /* 求解汉诺塔：问题 f(i) */
-    public void DFS(int i, List<int> src, List<int> buf, List<int> tar) {
+    void DFS(int i, List<int> src, List<int> buf, List<int> tar) {
         // 若 src 只剩下一个圆盘，则直接将其移到 tar
         if (i == 1) {
             Move(src, tar);
@@ -32,7 +32,7 @@ public class hanota {
     }
 
     /* 求解汉诺塔 */
-    public void SolveHanota(List<int> A, List<int> B, List<int> C) {
+    void SolveHanota(List<int> A, List<int> B, List<int> C) {
         int n = A.Count;
         // 将 A 顶部 n 个圆盘借助 B 移到 C
         DFS(n, A, B, C);
@@ -41,9 +41,9 @@ public class hanota {
     [Test]
     public void Test() {
         // 列表尾部是柱子顶部
-        List<int> A = new() { 5, 4, 3, 2, 1 };
+        List<int> A = [5, 4, 3, 2, 1];
-        List<int> B = new();
+        List<int> B = [];
-        List<int> C = new();
+        List<int> C = [];
         Console.WriteLine("初始状态下：");
         Console.WriteLine("A = " + string.Join(", ", A));
         Console.WriteLine("B = " + string.Join(", ", B));

codes/csharp/chapter_dynamic_programming/climbing_stairs_backtrack.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class climbing_stairs_backtrack {
     /* 回溯 */
-    public void Backtrack(List<int> choices, int state, int n, List<int> res) {
+    void Backtrack(List<int> choices, int state, int n, List<int> res) {
         // 当爬到第 n 阶时，方案数量加 1
         if (state == n)
             res[0]++;
@@ -24,10 +24,10 @@ public class climbing_stairs_backtrack {
     }
 
     /* 爬楼梯：回溯 */
-    public int ClimbingStairsBacktrack(int n) {
+    int ClimbingStairsBacktrack(int n) {
-        List<int> choices = new() { 1, 2 }; // 可选择向上爬 1 或 2 阶
+        List<int> choices = [1, 2]; // 可选择向上爬 1 或 2 阶
         int state = 0; // 从第 0 阶开始爬
-        List<int> res = new() { 0 }; // 使用 res[0] 记录方案数量
+        List<int> res = [0]; // 使用 res[0] 记录方案数量
         Backtrack(choices, state, n, res);
         return res[0];
     }

codes/csharp/chapter_dynamic_programming/climbing_stairs_constraint_dp.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class climbing_stairs_constraint_dp {
     /* 带约束爬楼梯：动态规划 */
-    public int ClimbingStairsConstraintDP(int n) {
+    int ClimbingStairsConstraintDP(int n) {
         if (n == 1 || n == 2) {
             return 1;
         }

codes/csharp/chapter_dynamic_programming/climbing_stairs_dfs.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class climbing_stairs_dfs {
     /* 搜索 */
-    public int DFS(int i) {
+    int DFS(int i) {
         // 已知 dp[1] 和 dp[2] ，返回之
         if (i == 1 || i == 2)
             return i;
@@ -18,7 +18,7 @@ public class climbing_stairs_dfs {
     }
 
     /* 爬楼梯：搜索 */
-    public int ClimbingStairsDFS(int n) {
+    int ClimbingStairsDFS(int n) {
         return DFS(n);
     }
 

codes/csharp/chapter_dynamic_programming/climbing_stairs_dfs_mem.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class climbing_stairs_dfs_mem {
     /* 记忆化搜索 */
-    public int DFS(int i, int[] mem) {
+    int DFS(int i, int[] mem) {
         // 已知 dp[1] 和 dp[2] ，返回之
         if (i == 1 || i == 2)
             return i;
@@ -23,7 +23,7 @@ public class climbing_stairs_dfs_mem {
     }
 
     /* 爬楼梯：记忆化搜索 */
-    public int ClimbingStairsDFSMem(int n) {
+    int ClimbingStairsDFSMem(int n) {
         // mem[i] 记录爬到第 i 阶的方案总数，-1 代表无记录
         int[] mem = new int[n + 1];
         Array.Fill(mem, -1);

codes/csharp/chapter_dynamic_programming/climbing_stairs_dp.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class climbing_stairs_dp {
     /* 爬楼梯：动态规划 */
-    public int ClimbingStairsDP(int n) {
+    int ClimbingStairsDP(int n) {
         if (n == 1 || n == 2)
             return n;
         // 初始化 dp 表，用于存储子问题的解
@@ -24,7 +24,7 @@ public class climbing_stairs_dp {
     }
 
     /* 爬楼梯：空间优化后的动态规划 */
-    public int ClimbingStairsDPComp(int n) {
+    int ClimbingStairsDPComp(int n) {
         if (n == 1 || n == 2)
             return n;
         int a = 1, b = 2;

codes/csharp/chapter_dynamic_programming/coin_change.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class coin_change {
     /* 零钱兑换：动态规划 */
-    public int CoinChangeDP(int[] coins, int amt) {
+    int CoinChangeDP(int[] coins, int amt) {
         int n = coins.Length;
         int MAX = amt + 1;
         // 初始化 dp 表
@@ -33,7 +33,7 @@ public class coin_change {
     }
 
     /* 零钱兑换：空间优化后的动态规划 */
-    public int CoinChangeDPComp(int[] coins, int amt) {
+    int CoinChangeDPComp(int[] coins, int amt) {
         int n = coins.Length;
         int MAX = amt + 1;
         // 初始化 dp 表
@@ -57,7 +57,7 @@ public class coin_change {
 
     [Test]
     public void Test() {
-        int[] coins = { 1, 2, 5 };
+        int[] coins = [1, 2, 5];
         int amt = 4;
 
         // 动态规划

codes/csharp/chapter_dynamic_programming/coin_change_ii.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class coin_change_ii {
     /* 零钱兑换 II：动态规划 */
-    public int CoinChangeIIDP(int[] coins, int amt) {
+    int CoinChangeIIDP(int[] coins, int amt) {
         int n = coins.Length;
         // 初始化 dp 表
         int[,] dp = new int[n + 1, amt + 1];
@@ -32,7 +32,7 @@ public class coin_change_ii {
     }
 
     /* 零钱兑换 II：空间优化后的动态规划 */
-    public int CoinChangeIIDPComp(int[] coins, int amt) {
+    int CoinChangeIIDPComp(int[] coins, int amt) {
         int n = coins.Length;
         // 初始化 dp 表
         int[] dp = new int[amt + 1];
@@ -54,7 +54,7 @@ public class coin_change_ii {
 
     [Test]
     public void Test() {
-        int[] coins = { 1, 2, 5 };
+        int[] coins = [1, 2, 5];
         int amt = 5;
 
         // 动态规划

codes/csharp/chapter_dynamic_programming/edit_distance.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class edit_distance {
     /* 编辑距离：暴力搜索 */
-    public int EditDistanceDFS(string s, string t, int i, int j) {
+    int EditDistanceDFS(string s, string t, int i, int j) {
         // 若 s 和 t 都为空，则返回 0
         if (i == 0 && j == 0)
             return 0;
@@ -30,7 +30,7 @@ public class edit_distance {
     }
 
     /* 编辑距离：记忆化搜索 */
-    public int EditDistanceDFSMem(string s, string t, int[][] mem, int i, int j) {
+    int EditDistanceDFSMem(string s, string t, int[][] mem, int i, int j) {
         // 若 s 和 t 都为空，则返回 0
         if (i == 0 && j == 0)
             return 0;
@@ -56,7 +56,7 @@ public class edit_distance {
     }
 
     /* 编辑距离：动态规划 */
-    public int EditDistanceDP(string s, string t) {
+    int EditDistanceDP(string s, string t) {
         int n = s.Length, m = t.Length;
         int[,] dp = new int[n + 1, m + 1];
         // 状态转移：首行首列
@@ -82,7 +82,7 @@ public class edit_distance {
     }
 
     /* 编辑距离：空间优化后的动态规划 */
-    public int EditDistanceDPComp(string s, string t) {
+    int EditDistanceDPComp(string s, string t) {
         int n = s.Length, m = t.Length;
         int[] dp = new int[m + 1];
         // 状态转移：首行

codes/csharp/chapter_dynamic_programming/knapsack.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class knapsack {
     /* 0-1 背包：暴力搜索 */
-    public int KnapsackDFS(int[] weight, int[] val, int i, int c) {
+    int KnapsackDFS(int[] weight, int[] val, int i, int c) {
         // 若已选完所有物品或背包无容量，则返回价值 0
         if (i == 0 || c == 0) {
             return 0;
@@ -25,7 +25,7 @@ public class knapsack {
     }
 
     /* 0-1 背包：记忆化搜索 */
-    public int KnapsackDFSMem(int[] weight, int[] val, int[][] mem, int i, int c) {
+    int KnapsackDFSMem(int[] weight, int[] val, int[][] mem, int i, int c) {
         // 若已选完所有物品或背包无容量，则返回价值 0
         if (i == 0 || c == 0) {
             return 0;
@@ -47,7 +47,7 @@ public class knapsack {
     }
 
     /* 0-1 背包：动态规划 */
-    public int KnapsackDP(int[] weight, int[] val, int cap) {
+    int KnapsackDP(int[] weight, int[] val, int cap) {
         int n = weight.Length;
         // 初始化 dp 表
         int[,] dp = new int[n + 1, cap + 1];
@@ -67,7 +67,7 @@ public class knapsack {
     }
 
     /* 0-1 背包：空间优化后的动态规划 */
-    public int KnapsackDPComp(int[] weight, int[] val, int cap) {
+    int KnapsackDPComp(int[] weight, int[] val, int cap) {
         int n = weight.Length;
         // 初始化 dp 表
         int[] dp = new int[cap + 1];
@@ -89,8 +89,8 @@ public class knapsack {
 
     [Test]
     public void Test() {
-        int[] weight = { 10, 20, 30, 40, 50 };
+        int[] weight = [10, 20, 30, 40, 50];
-        int[] val = { 50, 120, 150, 210, 240 };
+        int[] val = [50, 120, 150, 210, 240];
         int cap = 50;
         int n = weight.Length;
 

codes/csharp/chapter_dynamic_programming/min_cost_climbing_stairs_dp.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class min_cost_climbing_stairs_dp {
     /* 爬楼梯最小代价：动态规划 */
-    public int MinCostClimbingStairsDP(int[] cost) {
+    int MinCostClimbingStairsDP(int[] cost) {
         int n = cost.Length - 1;
         if (n == 1 || n == 2)
             return cost[n];
@@ -25,7 +25,7 @@ public class min_cost_climbing_stairs_dp {
     }
 
     /* 爬楼梯最小代价：空间优化后的动态规划 */
-    public int MinCostClimbingStairsDPComp(int[] cost) {
+    int MinCostClimbingStairsDPComp(int[] cost) {
         int n = cost.Length - 1;
         if (n == 1 || n == 2)
             return cost[n];
@@ -40,7 +40,7 @@ public class min_cost_climbing_stairs_dp {
 
     [Test]
     public void Test() {
-        int[] cost = { 0, 1, 10, 1, 1, 1, 10, 1, 1, 10, 1 };
+        int[] cost = [0, 1, 10, 1, 1, 1, 10, 1, 1, 10, 1];
         Console.WriteLine("输入楼梯的代价列表为");
         PrintUtil.PrintList(cost);
 

codes/csharp/chapter_dynamic_programming/min_path_sum.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class min_path_sum {
     /* 最小路径和：暴力搜索 */
-    public int MinPathSumDFS(int[][] grid, int i, int j) {
+    int MinPathSumDFS(int[][] grid, int i, int j) {
         // 若为左上角单元格，则终止搜索
         if (i == 0 && j == 0) {
             return grid[0][0];
@@ -25,7 +25,7 @@ public class min_path_sum {
     }
 
     /* 最小路径和：记忆化搜索 */
-    public int MinPathSumDFSMem(int[][] grid, int[][] mem, int i, int j) {
+    int MinPathSumDFSMem(int[][] grid, int[][] mem, int i, int j) {
         // 若为左上角单元格，则终止搜索
         if (i == 0 && j == 0) {
             return grid[0][0];
@@ -47,7 +47,7 @@ public class min_path_sum {
     }
 
     /* 最小路径和：动态规划 */
-    public int MinPathSumDP(int[][] grid) {
+    int MinPathSumDP(int[][] grid) {
         int n = grid.Length, m = grid[0].Length;
         // 初始化 dp 表
         int[,] dp = new int[n, m];
@@ -70,7 +70,7 @@ public class min_path_sum {
     }
 
     /* 最小路径和：空间优化后的动态规划 */
-    public int MinPathSumDPComp(int[][] grid) {
+    int MinPathSumDPComp(int[][] grid) {
         int n = grid.Length, m = grid[0].Length;
         // 初始化 dp 表
         int[] dp = new int[m];
@@ -94,12 +94,12 @@ public class min_path_sum {
     [Test]
     public void Test() {
         int[][] grid =
-        {
+        [
-            new int[4] { 1, 3, 1, 5 },
+            [1, 3, 1, 5],
-            new int[4] { 2, 2, 4, 2 },
+            [2, 2, 4, 2],
-            new int[4] { 5, 3, 2, 1 },
+            [5, 3, 2, 1],
-            new int[4] { 4, 3, 5, 2 }
+            [4, 3, 5, 2]
-        };
+        ];
 
         int n = grid.Length, m = grid[0].Length;
 

codes/csharp/chapter_dynamic_programming/unbounded_knapsack.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_dynamic_programming;
 
 public class unbounded_knapsack {
     /* 完全背包：动态规划 */
-    public int UnboundedKnapsackDP(int[] wgt, int[] val, int cap) {
+    int UnboundedKnapsackDP(int[] wgt, int[] val, int cap) {
         int n = wgt.Length;
         // 初始化 dp 表
         int[,] dp = new int[n + 1, cap + 1];
@@ -28,7 +28,7 @@ public class unbounded_knapsack {
     }
 
     /* 完全背包：空间优化后的动态规划 */
-    public int UnboundedKnapsackDPComp(int[] wgt, int[] val, int cap) {
+    int UnboundedKnapsackDPComp(int[] wgt, int[] val, int cap) {
         int n = wgt.Length;
         // 初始化 dp 表
         int[] dp = new int[cap + 1];
@@ -49,8 +49,8 @@ public class unbounded_knapsack {
 
     [Test]
     public void Test() {
-        int[] wgt = { 1, 2, 3 };
+        int[] wgt = [1, 2, 3];
-        int[] val = { 5, 11, 15 };
+        int[] val = [5, 11, 15];
         int cap = 4;
 
         // 动态规划

codes/csharp/chapter_graph/graph_adjacency_list.cs

@@ -13,7 +13,7 @@ public class GraphAdjList {
 
     /* 构造函数 */
     public GraphAdjList(Vertex[][] edges) {
-        this.adjList = new Dictionary<Vertex, List<Vertex>>();
+        adjList = [];
         // 添加所有顶点和边
         foreach (Vertex[] edge in edges) {
             AddVertex(edge[0]);
@@ -23,7 +23,7 @@ public class GraphAdjList {
     }
 
     /* 获取顶点数量 */
-    public int Size() {
+    int Size() {
         return adjList.Count;
     }
 
@@ -50,7 +50,7 @@ public class GraphAdjList {
         if (adjList.ContainsKey(vet))
             return;
         // 在邻接表中添加一个新链表
-        adjList.Add(vet, new List<Vertex>());
+        adjList.Add(vet, []);
     }
 
     /* 删除顶点 */
@@ -69,7 +69,7 @@ public class GraphAdjList {
     public void Print() {
         Console.WriteLine("邻接表 =");
         foreach (KeyValuePair<Vertex, List<Vertex>> pair in adjList) {
-            List<int> tmp = new();
+            List<int> tmp = [];
             foreach (Vertex vertex in pair.Value)
                 tmp.Add(vertex.val);
             Console.WriteLine(pair.Key.val + ": [" + string.Join(", ", tmp) + "],");
@@ -81,10 +81,16 @@ public class graph_adjacency_list {
     [Test]
     public void Test() {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.ValsToVets(new int[] { 1, 3, 2, 5, 4 });
+        Vertex[] v = Vertex.ValsToVets([1, 3, 2, 5, 4]);
-        Vertex[][] edges = new Vertex[][] { new Vertex[] { v[0], v[1] }, new Vertex[] { v[0], v[3] },
+        Vertex[][] edges =
-                                            new Vertex[] { v[1], v[2] }, new Vertex[] { v[2], v[3] },
+        [
-                                            new Vertex[] { v[2], v[4] }, new Vertex[] { v[3], v[4] } };
+            [v[0], v[1]],
+            [v[0], v[3]],
+            [v[1], v[2]],
+            [v[2], v[3]],
+            [v[2], v[4]],
+            [v[3], v[4]] 
+        ];
         GraphAdjList graph = new(edges);
         Console.WriteLine("\n初始化后，图为");
         graph.Print();

codes/csharp/chapter_graph/graph_adjacency_matrix.cs

@@ -8,13 +8,13 @@ namespace hello_algo.chapter_graph;
 
 /* 基于邻接矩阵实现的无向图类 */
 class GraphAdjMat {
-    readonly List<int> vertices;     // 顶点列表，元素代表“顶点值”，索引代表“顶点索引”
+    List<int> vertices;     // 顶点列表，元素代表“顶点值”，索引代表“顶点索引”
-    readonly List<List<int>> adjMat; // 邻接矩阵，行列索引对应“顶点索引”
+    List<List<int>> adjMat; // 邻接矩阵，行列索引对应“顶点索引”
 
     /* 构造函数 */
     public GraphAdjMat(int[] vertices, int[][] edges) {
-        this.vertices = new List<int>();
+        this.vertices = [];
-        this.adjMat = new List<List<int>>();
+        this.adjMat = [];
         // 添加顶点
         foreach (int val in vertices) {
             AddVertex(val);
@@ -27,7 +27,7 @@ class GraphAdjMat {
     }
 
     /* 获取顶点数量 */
-    public int Size() {
+    int Size() {
         return vertices.Count;
     }
 
@@ -97,10 +97,16 @@ public class graph_adjacency_matrix {
     public void Test() {
         /* 初始化无向图 */
         // 请注意，edges 元素代表顶点索引，即对应 vertices 元素索引
-        int[] vertices = { 1, 3, 2, 5, 4 };
+        int[] vertices = [1, 3, 2, 5, 4];
-        int[][] edges = new int[][] { new int[] { 0, 1 }, new int[] { 0, 3 },
+        int[][] edges = 
-                                      new int[] { 1, 2 }, new int[] { 2, 3 },
+        [
-                                      new int[] { 2, 4 }, new int[] { 3, 4 } };
+            [0, 1],
+            [0, 3],
+            [1, 2],
+            [2, 3],
+            [2, 4],
+            [3, 4]
+        ];
         GraphAdjMat graph = new(vertices, edges);
         Console.WriteLine("\n初始化后，图为");
         graph.Print();

codes/csharp/chapter_graph/graph_bfs.cs

@@ -9,11 +9,11 @@ namespace hello_algo.chapter_graph;
 public class graph_bfs {
     /* 广度优先遍历 BFS */
     // 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
-    public static List<Vertex> GraphBFS(GraphAdjList graph, Vertex startVet) {
+    List<Vertex> GraphBFS(GraphAdjList graph, Vertex startVet) {
         // 顶点遍历序列
-        List<Vertex> res = new();
+        List<Vertex> res = [];
         // 哈希表，用于记录已被访问过的顶点
-        HashSet<Vertex> visited = new() { startVet };
+        HashSet<Vertex> visited = [startVet];
         // 队列用于实现 BFS
         Queue<Vertex> que = new();
         que.Enqueue(startVet);
@@ -37,14 +37,14 @@ public class graph_bfs {
     [Test]
     public void Test() {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.ValsToVets(new int[10] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
+        Vertex[] v = Vertex.ValsToVets([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
-        Vertex[][] edges = new Vertex[12][]
+        Vertex[][] edges =
-        {
+        [
-            new Vertex[2] { v[0], v[1] }, new Vertex[2] { v[0], v[3] }, new Vertex[2] { v[1], v[2] },
+            [v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
-            new Vertex[2] { v[1], v[4] }, new Vertex[2] { v[2], v[5] }, new Vertex[2] { v[3], v[4] },
+            [v[1], v[4]], [v[2], v[5]], [v[3], v[4]],
-            new Vertex[2] { v[3], v[6] }, new Vertex[2] { v[4], v[5] }, new Vertex[2] { v[4], v[7] },
+            [v[3], v[6]], [v[4], v[5]], [v[4], v[7]],
-            new Vertex[2] { v[5], v[8] }, new Vertex[2] { v[6], v[7] }, new Vertex[2] { v[7], v[8] }
+            [v[5], v[8]], [v[6], v[7]], [v[7], v[8]]
-        };
+        ];
 
         GraphAdjList graph = new(edges);
         Console.WriteLine("\n初始化后，图为");

codes/csharp/chapter_graph/graph_dfs.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_graph;
 
 public class graph_dfs {
     /* 深度优先遍历 DFS 辅助函数 */
-    public void DFS(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet) {
+    void DFS(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet) {
         res.Add(vet);     // 记录访问顶点
         visited.Add(vet); // 标记该顶点已被访问
         // 遍历该顶点的所有邻接顶点
@@ -23,11 +23,11 @@ public class graph_dfs {
 
     /* 深度优先遍历 DFS */
     // 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
-    public List<Vertex> GraphDFS(GraphAdjList graph, Vertex startVet) {
+    List<Vertex> GraphDFS(GraphAdjList graph, Vertex startVet) {
         // 顶点遍历序列
-        List<Vertex> res = new();
+        List<Vertex> res = [];
         // 哈希表，用于记录已被访问过的顶点
-        HashSet<Vertex> visited = new();
+        HashSet<Vertex> visited = [];
         DFS(graph, visited, res, startVet);
         return res;
     }
@@ -35,12 +35,12 @@ public class graph_dfs {
     [Test]
     public void Test() {
         /* 初始化无向图 */
-        Vertex[] v = Vertex.ValsToVets(new int[7] { 0, 1, 2, 3, 4, 5, 6 });
+        Vertex[] v = Vertex.ValsToVets([0, 1, 2, 3, 4, 5, 6]);
-        Vertex[][] edges = new Vertex[6][]
+        Vertex[][] edges =
-        {
+        [
-            new Vertex[2] { v[0], v[1] }, new Vertex[2] { v[0], v[3] }, new Vertex[2] { v[1], v[2] },
+            [v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
-            new Vertex[2] { v[2], v[5] }, new Vertex[2] { v[4], v[5] }, new Vertex[2] { v[5], v[6] },
+            [v[2], v[5]], [v[4], v[5]], [v[5], v[6]],
-        };
+        ];
 
         GraphAdjList graph = new(edges);
         Console.WriteLine("\n初始化后，图为");

codes/csharp/chapter_greedy/coin_change_greedy.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_greedy;
 
 public class coin_change_greedy {
     /* 零钱兑换：贪心 */
-    public int CoinChangeGreedy(int[] coins, int amt) {
+    int CoinChangeGreedy(int[] coins, int amt) {
         // 假设 coins 列表有序
         int i = coins.Length - 1;
         int count = 0;
@@ -29,14 +29,14 @@ public class coin_change_greedy {
     [Test]
     public void Test() {
         // 贪心：能够保证找到全局最优解
-        int[] coins = { 1, 5, 10, 20, 50, 100 };
+        int[] coins = [1, 5, 10, 20, 50, 100];
         int amt = 186;
         int res = CoinChangeGreedy(coins, amt);
         Console.WriteLine("\ncoins = " + coins.PrintList() + ", amt = " + amt);
         Console.WriteLine("凑到 " + amt + " 所需的最少硬币数量为 " + res);
 
         // 贪心：无法保证找到全局最优解
-        coins = new int[] { 1, 20, 50 };
+        coins = [1, 20, 50];
         amt = 60;
         res = CoinChangeGreedy(coins, amt);
         Console.WriteLine("\ncoins = " + coins.PrintList() + ", amt = " + amt);
@@ -44,7 +44,7 @@ public class coin_change_greedy {
         Console.WriteLine("实际上需要的最少数量为 3 ，即 20 + 20 + 20");
 
         // 贪心：无法保证找到全局最优解
-        coins = new int[] { 1, 49, 50 };
+        coins = [1, 49, 50];
         amt = 98;
         res = CoinChangeGreedy(coins, amt);
         Console.WriteLine("\ncoins = " + coins.PrintList() + ", amt = " + amt);

codes/csharp/chapter_greedy/fractional_knapsack.cs

@@ -7,19 +7,14 @@
 namespace hello_algo.chapter_greedy;
 
 /* 物品 */
-class Item {
+class Item(int w, int v) {
-    public int w; // 物品重量
+    public int w = w; // 物品重量
-    public int v; // 物品价值
+    public int v = v; // 物品价值
-
-    public Item(int w, int v) {
-        this.w = w;
-        this.v = v;
-    }
 }
 
 public class fractional_knapsack {
     /* 分数背包：贪心 */
-    public double FractionalKnapsack(int[] wgt, int[] val, int cap) {
+    double FractionalKnapsack(int[] wgt, int[] val, int cap) {
         // 创建物品列表，包含两个属性：重量、价值
         Item[] items = new Item[wgt.Length];
         for (int i = 0; i < wgt.Length; i++) {
@@ -46,8 +41,8 @@ public class fractional_knapsack {
 
     [Test]
     public void Test() {
-        int[] wgt = { 10, 20, 30, 40, 50 };
+        int[] wgt = [10, 20, 30, 40, 50];
-        int[] val = { 50, 120, 150, 210, 240 };
+        int[] val = [50, 120, 150, 210, 240];
         int cap = 50;
 
         // 贪心算法

codes/csharp/chapter_greedy/max_capacity.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_greedy;
 
 public class max_capacity {
     /* 最大容量：贪心 */
-    public int MaxCapacity(int[] ht) {
+    int MaxCapacity(int[] ht) {
         // 初始化 i, j 分列数组两端
         int i = 0, j = ht.Length - 1;
         // 初始最大容量为 0
@@ -30,7 +30,7 @@ public class max_capacity {
 
     [Test]
     public void Test() {
-        int[] ht = { 3, 8, 5, 2, 7, 7, 3, 4 };
+        int[] ht = [3, 8, 5, 2, 7, 7, 3, 4];
 
         // 贪心算法
         int res = MaxCapacity(ht);

codes/csharp/chapter_greedy/max_product_cutting.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_greedy;
 
 public class max_product_cutting {
     /* 最大切分乘积：贪心 */
-    public int MaxProductCutting(int n) {
+    int MaxProductCutting(int n) {
         // 当 n <= 3 时，必须切分出一个 1
         if (n <= 3) {
             return 1 * (n - 1);

codes/csharp/chapter_hashing/array_hash_map.cs

@@ -7,28 +7,24 @@
 namespace hello_algo.chapter_hashing;
 
 /* 键值对 int->string */
-class Pair {
+class Pair(int key, string val) {
-    public int key;
+    public int key = key;
-    public string val;
+    public string val = val;
-    public Pair(int key, string val) {
-        this.key = key;
-        this.val = val;
-    }
 }
 
 /* 基于数组简易实现的哈希表 */
 class ArrayHashMap {
-    private readonly List<Pair?> buckets;
+    List<Pair?> buckets;
     public ArrayHashMap() {
         // 初始化数组，包含 100 个桶
-        buckets = new();
+        buckets = [];
         for (int i = 0; i < 100; i++) {
             buckets.Add(null);
         }
     }
 
     /* 哈希函数 */
-    private int HashFunc(int key) {
+    int HashFunc(int key) {
         int index = key % 100;
         return index;
     }
@@ -57,7 +53,7 @@ class ArrayHashMap {
 
     /* 获取所有键值对 */
     public List<Pair> PairSet() {
-        List<Pair> pairSet = new();
+        List<Pair> pairSet = [];
         foreach (Pair? pair in buckets) {
             if (pair != null)
                 pairSet.Add(pair);
@@ -67,7 +63,7 @@ class ArrayHashMap {
 
     /* 获取所有键 */
     public List<int> KeySet() {
-        List<int> keySet = new();
+        List<int> keySet = [];
         foreach (Pair? pair in buckets) {
             if (pair != null)
                 keySet.Add(pair.key);
@@ -77,7 +73,7 @@ class ArrayHashMap {
 
     /* 获取所有值 */
     public List<string> ValueSet() {
-        List<string> valueSet = new();
+        List<string> valueSet = [];
         foreach (Pair? pair in buckets) {
             if (pair != null)
                 valueSet.Add(pair.val);

codes/csharp/chapter_hashing/built_in_hash.cs

@@ -25,7 +25,7 @@ public class built_in_hash {
         int hashStr = str.GetHashCode();
         Console.WriteLine("字符串 " + str + " 的哈希值为 " + hashStr);
 
-        object[] arr = { 12836, "小哈" };
+        object[] arr = [12836, "小哈"];
         int hashTup = arr.GetHashCode();
         Console.WriteLine("数组 [" + string.Join(", ", arr) + "] 的哈希值为 " + hashTup);
 

codes/csharp/chapter_hashing/hash_map_chaining.cs

@@ -10,8 +10,8 @@ namespace hello_algo.chapter_hashing;
 class HashMapChaining {
     int size; // 键值对数量
     int capacity; // 哈希表容量
-    readonly double loadThres; // 触发扩容的负载因子阈值
+    double loadThres; // 触发扩容的负载因子阈值
-    readonly int extendRatio; // 扩容倍数
+    int extendRatio; // 扩容倍数
     List<List<Pair>> buckets; // 桶数组
 
     /* 构造方法 */
@@ -22,17 +22,17 @@ class HashMapChaining {
         extendRatio = 2;
         buckets = new List<List<Pair>>(capacity);
         for (int i = 0; i < capacity; i++) {
-            buckets.Add(new List<Pair>());
+            buckets.Add([]);
         }
     }
 
     /* 哈希函数 */
-    private int HashFunc(int key) {
+    int HashFunc(int key) {
         return key % capacity;
     }
 
     /* 负载因子 */
-    private double LoadFactor() {
+    double LoadFactor() {
         return (double)size / capacity;
     }
 
@@ -82,14 +82,14 @@ class HashMapChaining {
     }
 
     /* 扩容哈希表 */
-    private void Extend() {
+    void Extend() {
         // 暂存原哈希表
         List<List<Pair>> bucketsTmp = buckets;
         // 初始化扩容后的新哈希表
         capacity *= extendRatio;
         buckets = new List<List<Pair>>(capacity);
         for (int i = 0; i < capacity; i++) {
-            buckets.Add(new List<Pair>());
+            buckets.Add([]);
         }
         size = 0;
         // 将键值对从原哈希表搬运至新哈希表
@@ -103,7 +103,7 @@ class HashMapChaining {
     /* 打印哈希表 */
     public void Print() {
         foreach (List<Pair> bucket in buckets) {
-            List<string> res = new();
+            List<string> res = [];
             foreach (Pair pair in bucket) {
                 res.Add(pair.key + " -> " + pair.val);
             }

codes/csharp/chapter_hashing/hash_map_open_addressing.cs

@@ -8,12 +8,12 @@ namespace hello_algo.chapter_hashing;
 
 /* 开放寻址哈希表 */
 class HashMapOpenAddressing {
-    private int size; // 键值对数量
+    int size; // 键值对数量
-    private int capacity = 4; // 哈希表容量
+    int capacity = 4; // 哈希表容量
-    private readonly double loadThres = 2.0 / 3.0; // 触发扩容的负载因子阈值
+    double loadThres = 2.0 / 3.0; // 触发扩容的负载因子阈值
-    private readonly int extendRatio = 2; // 扩容倍数
+    int extendRatio = 2; // 扩容倍数
-    private Pair[] buckets; // 桶数组
+    Pair[] buckets; // 桶数组
-    private readonly Pair TOMBSTONE = new(-1, "-1"); // 删除标记
+    Pair TOMBSTONE = new(-1, "-1"); // 删除标记
 
     /* 构造方法 */
     public HashMapOpenAddressing() {
@@ -22,17 +22,17 @@ class HashMapOpenAddressing {
     }
 
     /* 哈希函数 */
-    private int HashFunc(int key) {
+    int HashFunc(int key) {
         return key % capacity;
     }
 
     /* 负载因子 */
-    private double LoadFactor() {
+    double LoadFactor() {
         return (double)size / capacity;
     }
 
     /* 搜索 key 对应的桶索引 */
-    private int FindBucket(int key) {
+    int FindBucket(int key) {
         int index = HashFunc(key);
         int firstTombstone = -1;
         // 线性探测，当遇到空桶时跳出
@@ -100,7 +100,7 @@ class HashMapOpenAddressing {
     }
 
     /* 扩容哈希表 */
-    private void Extend() {
+    void Extend() {
         // 暂存原哈希表
         Pair[] bucketsTmp = buckets;
         // 初始化扩容后的新哈希表

codes/csharp/chapter_hashing/simple_hash.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_hashing;
 
 public class simple_hash {
     /* 加法哈希 */
-    public static int AddHash(string key) {
+    int AddHash(string key) {
         long hash = 0;
         const int MODULUS = 1000000007;
         foreach (char c in key) {
@@ -18,7 +18,7 @@ public class simple_hash {
     }
 
     /* 乘法哈希 */
-    public static int MulHash(string key) {
+    int MulHash(string key) {
         long hash = 0;
         const int MODULUS = 1000000007;
         foreach (char c in key) {
@@ -28,7 +28,7 @@ public class simple_hash {
     }
 
     /* 异或哈希 */
-    public static int XorHash(string key) {
+    int XorHash(string key) {
         int hash = 0;
         const int MODULUS = 1000000007;
         foreach (char c in key) {
@@ -38,7 +38,7 @@ public class simple_hash {
     }
 
     /* 旋转哈希 */
-    public static int RotHash(string key) {
+    int RotHash(string key) {
         long hash = 0;
         const int MODULUS = 1000000007;
         foreach (char c in key) {

codes/csharp/chapter_heap/heap.cs

@@ -7,13 +7,13 @@
 namespace hello_algo.chapter_heap;
 
 public class heap {
-    public void TestPush(PriorityQueue<int, int> heap, int val) {
+    void TestPush(PriorityQueue<int, int> heap, int val) {
         heap.Enqueue(val, val); // 元素入堆
         Console.WriteLine($"\n元素 {val} 入堆后\n");
         PrintUtil.PrintHeap(heap);
     }
 
-    public void TestPop(PriorityQueue<int, int> heap) {
+    void TestPop(PriorityQueue<int, int> heap) {
         int val = heap.Dequeue(); // 堆顶元素出堆
         Console.WriteLine($"\n堆顶元素 {val} 出堆后\n");
         PrintUtil.PrintHeap(heap);

codes/csharp/chapter_heap/my_heap.cs

@@ -9,11 +9,11 @@ namespace hello_algo.chapter_heap;
 /* 大顶堆 */
 class MaxHeap {
     // 使用列表而非数组，这样无须考虑扩容问题
-    private readonly List<int> maxHeap;
+    List<int> maxHeap;
 
     /* 构造函数，建立空堆 */
     public MaxHeap() {
-        maxHeap = new List<int>();
+        maxHeap = [];
     }
 
     /* 构造函数，根据输入列表建堆 */
@@ -130,7 +130,7 @@ public class my_heap {
     [Test]
     public void Test() {
         /* 初始化大顶堆 */
-        MaxHeap maxHeap = new(new int[] { 9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2 });
+        MaxHeap maxHeap = new([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]);
         Console.WriteLine("\n输入列表并建堆后");
         maxHeap.Print();
 

codes/csharp/chapter_heap/top_k.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_heap;
 
 public class top_k {
     /* 基于堆查找数组中最大的 k 个元素 */
-    public static PriorityQueue<int, int> TopKHeap(int[] nums, int k) {
+    PriorityQueue<int, int> TopKHeap(int[] nums, int k) {
         // 初始化小顶堆
         PriorityQueue<int, int> heap = new();
         // 将数组的前 k 个元素入堆
@@ -28,7 +28,7 @@ public class top_k {
 
     [Test]
     public void Test() {
-        int[] nums = { 1, 7, 6, 3, 2 };
+        int[] nums = [1, 7, 6, 3, 2];
         int k = 3;
         PriorityQueue<int, int> res = TopKHeap(nums, k);
         Console.WriteLine("最大的 " + k + " 个元素为");

codes/csharp/chapter_searching/binary_search.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_searching;
 
 public class binary_search {
     /* 二分查找（双闭区间） */
-    static int BinarySearch(int[] nums, int target) {
+    int BinarySearch(int[] nums, int target) {
         // 初始化双闭区间 [0, n-1] ，即 i, j 分别指向数组首元素、尾元素
         int i = 0, j = nums.Length - 1;
         // 循环，当搜索区间为空时跳出（当 i > j 时为空）
@@ -26,7 +26,7 @@ public class binary_search {
     }
 
     /* 二分查找（左闭右开） */
-    static int BinarySearchLCRO(int[] nums, int target) {
+    int BinarySearchLCRO(int[] nums, int target) {
         // 初始化左闭右开 [0, n) ，即 i, j 分别指向数组首元素、尾元素+1
         int i = 0, j = nums.Length;
         // 循环，当搜索区间为空时跳出（当 i = j 时为空）
@@ -46,7 +46,7 @@ public class binary_search {
     [Test]
     public void Test() {
         int target = 6;
-        int[] nums = { 1, 3, 6, 8, 12, 15, 23, 26, 31, 35 };
+        int[] nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
 
         /* 二分查找（双闭区间） */
         int index = BinarySearch(nums, target);

codes/csharp/chapter_searching/binary_search_edge.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_searching;
 
 public class binary_search_edge {
     /* 二分查找最左一个 target */
-    public int BinarySearchLeftEdge(int[] nums, int target) {
+    int BinarySearchLeftEdge(int[] nums, int target) {
         // 等价于查找 target 的插入点
         int i = binary_search_insertion.BinarySearchInsertion(nums, target);
         // 未找到 target ，返回 -1
@@ -20,7 +20,7 @@ public class binary_search_edge {
     }
 
     /* 二分查找最右一个 target */
-    public int BinarySearchRightEdge(int[] nums, int target) {
+    int BinarySearchRightEdge(int[] nums, int target) {
         // 转化为查找最左一个 target + 1
         int i = binary_search_insertion.BinarySearchInsertion(nums, target + 1);
         // j 指向最右一个 target ，i 指向首个大于 target 的元素
@@ -36,7 +36,7 @@ public class binary_search_edge {
     [Test]
     public void Test() {
         // 包含重复元素的数组
-        int[] nums = { 1, 3, 6, 6, 6, 6, 6, 10, 12, 15 };
+        int[] nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15];
         Console.WriteLine("\n数组 nums = " + nums.PrintList());
 
         // 二分查找左边界和右边界

codes/csharp/chapter_searching/binary_search_insertion.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_searching;
 
 public class binary_search_insertion {
     /* 二分查找插入点（无重复元素） */
-    public int BinarySearchInsertionSimple(int[] nums, int target) {
+    public static int BinarySearchInsertionSimple(int[] nums, int target) {
         int i = 0, j = nums.Length - 1; // 初始化双闭区间 [0, n-1]
         while (i <= j) {
             int m = i + (j - i) / 2; // 计算中点索引 m
@@ -44,7 +44,7 @@ public class binary_search_insertion {
     [Test]
     public void Test() {
         // 无重复元素的数组
-        int[] nums = { 1, 3, 6, 8, 12, 15, 23, 26, 31, 35 };
+        int[] nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35];
         Console.WriteLine("\n数组 nums = " + nums.PrintList());
         // 二分查找插入点
         foreach (int target in new int[] { 6, 9 }) {
@@ -53,7 +53,7 @@ public class binary_search_insertion {
         }
 
         // 包含重复元素的数组
-        nums = new int[] { 1, 3, 6, 6, 6, 6, 6, 10, 12, 15 };
+        nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15];
         Console.WriteLine("\n数组 nums = " + nums.PrintList());
         // 二分查找插入点
         foreach (int target in new int[] { 2, 6, 20 }) {

codes/csharp/chapter_searching/hashing_search.cs

@@ -8,14 +8,14 @@ namespace hello_algo.chapter_searching;
 
 public class hashing_search {
     /* 哈希查找（数组） */
-    static int HashingSearchArray(Dictionary<int, int> map, int target) {
+    int HashingSearchArray(Dictionary<int, int> map, int target) {
         // 哈希表的 key: 目标元素，value: 索引
         // 若哈希表中无此 key ，返回 -1
         return map.GetValueOrDefault(target, -1);
     }
 
     /* 哈希查找（链表） */
-    static ListNode? HashingSearchLinkedList(Dictionary<int, ListNode> map, int target) {
+    ListNode? HashingSearchLinkedList(Dictionary<int, ListNode> map, int target) {
 
         // 哈希表的 key: 目标节点值，value: 节点对象
         // 若哈希表中无此 key ，返回 null
@@ -27,9 +27,9 @@ public class hashing_search {
         int target = 3;
 
         /* 哈希查找（数组） */
-        int[] nums = { 1, 5, 3, 2, 4, 7, 5, 9, 10, 8 };
+        int[] nums = [1, 5, 3, 2, 4, 7, 5, 9, 10, 8];
         // 初始化哈希表
-        Dictionary<int, int> map = new();
+        Dictionary<int, int> map = [];
         for (int i = 0; i < nums.Length; i++) {
             map[nums[i]] = i;  // key: 元素，value: 索引
         }
@@ -39,7 +39,7 @@ public class hashing_search {
         /* 哈希查找（链表） */
         ListNode? head = ListNode.ArrToLinkedList(nums);
         // 初始化哈希表
-        Dictionary<int, ListNode> map1 = new();
+        Dictionary<int, ListNode> map1 = [];
         while (head != null) {
             map1[head.val] = head;  // key: 节点值，value: 节点
             head = head.next;

codes/csharp/chapter_searching/linear_search.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_searching;
 
 public class linear_search {
     /* 线性查找（数组） */
-    static int LinearSearchArray(int[] nums, int target) {
+    int LinearSearchArray(int[] nums, int target) {
         // 遍历数组
         for (int i = 0; i < nums.Length; i++) {
             // 找到目标元素，返回其索引
@@ -20,7 +20,7 @@ public class linear_search {
     }
 
     /* 线性查找（链表） */
-    static ListNode? LinearSearchLinkedList(ListNode? head, int target) {
+    ListNode? LinearSearchLinkedList(ListNode? head, int target) {
         // 遍历链表
         while (head != null) {
             // 找到目标节点，返回之
@@ -37,7 +37,7 @@ public class linear_search {
         int target = 3;
 
         /* 在数组中执行线性查找 */
-        int[] nums = { 1, 5, 3, 2, 4, 7, 5, 9, 10, 8 };
+        int[] nums = [1, 5, 3, 2, 4, 7, 5, 9, 10, 8];
         int index = LinearSearchArray(nums, target);
         Console.WriteLine("目标元素 3 的索引 = " + index);
 

codes/csharp/chapter_searching/two_sum.cs

@@ -8,37 +8,37 @@ namespace hello_algo.chapter_searching;
 
 public class two_sum {
     /* 方法一：暴力枚举 */
-    public static int[] TwoSumBruteForce(int[] nums, int target) {
+    int[] TwoSumBruteForce(int[] nums, int target) {
         int size = nums.Length;
         // 两层循环，时间复杂度 O(n^2)
         for (int i = 0; i < size - 1; i++) {
             for (int j = i + 1; j < size; j++) {
                 if (nums[i] + nums[j] == target)
-                    return new int[] { i, j };
+                    return [i, j];
             }
         }
-        return Array.Empty<int>();
+        return [];
     }
 
     /* 方法二：辅助哈希表 */
-    public static int[] TwoSumHashTable(int[] nums, int target) {
+    int[] TwoSumHashTable(int[] nums, int target) {
         int size = nums.Length;
         // 辅助哈希表，空间复杂度 O(n)
-        Dictionary<int, int> dic = new();
+        Dictionary<int, int> dic = [];
         // 单层循环，时间复杂度 O(n)
         for (int i = 0; i < size; i++) {
             if (dic.ContainsKey(target - nums[i])) {
-                return new int[] { dic[target - nums[i]], i };
+                return [dic[target - nums[i]], i];
             }
             dic.Add(nums[i], i);
         }
-        return Array.Empty<int>();
+        return [];
     }
 
     [Test]
     public void Test() {
         // ======= Test Case =======
-        int[] nums = { 2, 7, 11, 15 };
+        int[] nums = [2, 7, 11, 15];
         int target = 13;
 
         // ====== Driver Code ======

codes/csharp/chapter_sorting/bubble_sort.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_sorting;
 
 public class bubble_sort {
     /* 冒泡排序 */
-    static void BubbleSort(int[] nums) {
+    void BubbleSort(int[] nums) {
         // 外循环：未排序区间为 [0, i]
         for (int i = nums.Length - 1; i > 0; i--) {
             // 内循环：将未排序区间 [0, i] 中的最大元素交换至该区间的最右端 
@@ -22,7 +22,7 @@ public class bubble_sort {
     }
 
     /* 冒泡排序（标志优化）*/
-    static void BubbleSortWithFlag(int[] nums) {
+    void BubbleSortWithFlag(int[] nums) {
         // 外循环：未排序区间为 [0, i]
         for (int i = nums.Length - 1; i > 0; i--) {
             bool flag = false; // 初始化标志位
@@ -40,11 +40,11 @@ public class bubble_sort {
 
     [Test]
     public void Test() {
-        int[] nums = { 4, 1, 3, 1, 5, 2 };
+        int[] nums = [4, 1, 3, 1, 5, 2];
         BubbleSort(nums);
         Console.WriteLine("冒泡排序完成后  nums = " + string.Join(",", nums));
 
-        int[] nums1 = { 4, 1, 3, 1, 5, 2 };
+        int[] nums1 = [4, 1, 3, 1, 5, 2];
         BubbleSortWithFlag(nums1);
         Console.WriteLine("冒泡排序完成后 nums1 = " + string.Join(",", nums1));
     }

codes/csharp/chapter_sorting/bucket_sort.cs

@@ -8,12 +8,12 @@ namespace hello_algo.chapter_sorting;
 
 public class bucket_sort {
     /* 桶排序 */
-    public static void BucketSort(float[] nums) {
+    void BucketSort(float[] nums) {
         // 初始化 k = n/2 个桶，预期向每个桶分配 2 个元素
         int k = nums.Length / 2;
-        List<List<float>> buckets = new();
+        List<List<float>> buckets = [];
         for (int i = 0; i < k; i++) {
-            buckets.Add(new List<float>());
+            buckets.Add([]);
         }
         // 1. 将数组元素分配到各个桶中
         foreach (float num in nums) {
@@ -39,7 +39,7 @@ public class bucket_sort {
     [Test]
     public void Test() {
         // 设输入数据为浮点数，范围为 [0, 1)
-        float[] nums = { 0.49f, 0.96f, 0.82f, 0.09f, 0.57f, 0.43f, 0.91f, 0.75f, 0.15f, 0.37f };
+        float[] nums = [0.49f, 0.96f, 0.82f, 0.09f, 0.57f, 0.43f, 0.91f, 0.75f, 0.15f, 0.37f];
         BucketSort(nums);
         Console.WriteLine("桶排序完成后 nums = " + string.Join(" ", nums));
     }

codes/csharp/chapter_sorting/counting_sort.cs

@@ -9,7 +9,7 @@ namespace hello_algo.chapter_sorting;
 public class counting_sort {
     /* 计数排序 */
     // 简单实现，无法用于排序对象
-    public static void CountingSortNaive(int[] nums) {
+    void CountingSortNaive(int[] nums) {
         // 1. 统计数组最大元素 m
         int m = 0;
         foreach (int num in nums) {
@@ -32,7 +32,7 @@ public class counting_sort {
 
     /* 计数排序 */
     // 完整实现，可排序对象，并且是稳定排序
-    static void CountingSort(int[] nums) {
+    void CountingSort(int[] nums) {
         // 1. 统计数组最大元素 m
         int m = 0;
         foreach (int num in nums) {
@@ -66,11 +66,11 @@ public class counting_sort {
 
     [Test]
     public void Test() {
-        int[] nums = { 1, 0, 1, 2, 0, 4, 0, 2, 2, 4 };
+        int[] nums = [1, 0, 1, 2, 0, 4, 0, 2, 2, 4];
         CountingSortNaive(nums);
         Console.WriteLine("计数排序（无法排序对象）完成后 nums = " + string.Join(" ", nums));
 
-        int[] nums1 = { 1, 0, 1, 2, 0, 4, 0, 2, 2, 4 };
+        int[] nums1 = [1, 0, 1, 2, 0, 4, 0, 2, 2, 4];
         CountingSort(nums1);
         Console.WriteLine("计数排序完成后 nums1 = " + string.Join(" ", nums));
     }

codes/csharp/chapter_sorting/heap_sort.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_sorting;
 
 public class heap_sort {
     /* 堆的长度为 n ，从节点 i 开始，从顶至底堆化 */
-    public static void SiftDown(int[] nums, int n, int i) {
+    void SiftDown(int[] nums, int n, int i) {
         while (true) {
             // 判断节点 i, l, r 中值最大的节点，记为 ma
             int l = 2 * i + 1;
@@ -29,7 +29,7 @@ public class heap_sort {
     }
 
     /* 堆排序 */
-    public static void HeapSort(int[] nums) {
+    void HeapSort(int[] nums) {
         // 建堆操作：堆化除叶节点以外的其他所有节点
         for (int i = nums.Length / 2 - 1; i >= 0; i--) {
             SiftDown(nums, nums.Length, i);
@@ -45,7 +45,7 @@ public class heap_sort {
 
     [Test]
     public void Test() {
-        int[] nums = { 4, 1, 3, 1, 5, 2 };
+        int[] nums = [4, 1, 3, 1, 5, 2];
         HeapSort(nums);
         Console.WriteLine("堆排序完成后 nums = " + string.Join(" ", nums));
     }

codes/csharp/chapter_sorting/insertion_sort.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_sorting;
 
 public class insertion_sort {
     /* 插入排序 */
-    static void InsertionSort(int[] nums) {
+    void InsertionSort(int[] nums) {
         // 外循环：已排序元素数量为 1, 2, ..., n
         for (int i = 1; i < nums.Length; i++) {
             int bas = nums[i], j = i - 1;
@@ -23,7 +23,7 @@ public class insertion_sort {
 
     [Test]
     public void Test() {
-        int[] nums = { 4, 1, 3, 1, 5, 2 };
+        int[] nums = [4, 1, 3, 1, 5, 2];
         InsertionSort(nums);
         Console.WriteLine("插入排序完成后 nums = " + string.Join(",", nums));
     }

codes/csharp/chapter_sorting/merge_sort.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_sorting;
 
 public class merge_sort {
     /* 合并左子数组和右子数组 */
-    static void Merge(int[] nums, int left, int mid, int right) {
+    void Merge(int[] nums, int left, int mid, int right) {
         // 左子数组区间 [left, mid], 右子数组区间 [mid+1, right]
         // 创建一个临时数组 tmp ，用于存放合并后的结果
         int[] tmp = new int[right - left + 1];
@@ -35,7 +35,7 @@ public class merge_sort {
     }
 
     /* 归并排序 */
-    static void MergeSort(int[] nums, int left, int right) {
+    void MergeSort(int[] nums, int left, int right) {
         // 终止条件
         if (left >= right) return;       // 当子数组长度为 1 时终止递归
         // 划分阶段
@@ -49,7 +49,7 @@ public class merge_sort {
     [Test]
     public void Test() {
         /* 归并排序 */
-        int[] nums = { 7, 3, 2, 6, 0, 1, 5, 4 };
+        int[] nums = [7, 3, 2, 6, 0, 1, 5, 4];
         MergeSort(nums, 0, nums.Length - 1);
         Console.WriteLine("归并排序完成后 nums = " + string.Join(",", nums));
     }

codes/csharp/chapter_sorting/quick_sort.cs

@@ -135,17 +135,17 @@ public class quick_sort {
     [Test]
     public void Test() {
         /* 快速排序 */
-        int[] nums = { 2, 4, 1, 0, 3, 5 };
+        int[] nums = [2, 4, 1, 0, 3, 5];
         quickSort.QuickSort(nums, 0, nums.Length - 1);
         Console.WriteLine("快速排序完成后 nums = " + string.Join(",", nums));
 
         /* 快速排序（中位基准数优化） */
-        int[] nums1 = { 2, 4, 1, 0, 3, 5 };
+        int[] nums1 = [2, 4, 1, 0, 3, 5];
         QuickSortMedian.QuickSort(nums1, 0, nums1.Length - 1);
         Console.WriteLine("快速排序（中位基准数优化）完成后 nums1 = " + string.Join(",", nums1));
 
         /* 快速排序（尾递归优化） */
-        int[] nums2 = { 2, 4, 1, 0, 3, 5 };
+        int[] nums2 = [2, 4, 1, 0, 3, 5];
         QuickSortTailCall.QuickSort(nums2, 0, nums2.Length - 1);
         Console.WriteLine("快速排序（尾递归优化）完成后 nums2 = " + string.Join(",", nums2));
     }

codes/csharp/chapter_sorting/radix_sort.cs

@@ -8,13 +8,13 @@ namespace hello_algo.chapter_sorting;
 
 public class radix_sort {
     /* 获取元素 num 的第 k 位，其中 exp = 10^(k-1) */
-    static int Digit(int num, int exp) {
+    int Digit(int num, int exp) {
         // 传入 exp 而非 k 可以避免在此重复执行昂贵的次方计算
         return (num / exp) % 10;
     }
 
     /* 计数排序（根据 nums 第 k 位排序） */
-    static void CountingSortDigit(int[] nums, int exp) {
+    void CountingSortDigit(int[] nums, int exp) {
         // 十进制的位范围为 0~9 ，因此需要长度为 10 的桶
         int[] counter = new int[10];
         int n = nums.Length;
@@ -42,7 +42,7 @@ public class radix_sort {
     }
 
     /* 基数排序 */
-    static void RadixSort(int[] nums) {
+    void RadixSort(int[] nums) {
         // 获取数组的最大元素，用于判断最大位数
         int m = int.MinValue;
         foreach (int num in nums) {
@@ -61,8 +61,8 @@ public class radix_sort {
     [Test]
     public void Test() {
         // 基数排序
-        int[] nums = { 10546151, 35663510, 42865989, 34862445, 81883077,
+        int[] nums = [ 10546151, 35663510, 42865989, 34862445, 81883077,
-            88906420, 72429244, 30524779, 82060337, 63832996 };
+            88906420, 72429244, 30524779, 82060337, 63832996 ];
         RadixSort(nums);
         Console.WriteLine("基数排序完成后 nums = " + string.Join(" ", nums));
     }

codes/csharp/chapter_sorting/selection_sort.cs

@@ -8,7 +8,7 @@ namespace hello_algo.chapter_sorting;
 
 public class selection_sort {
     /* 选择排序 */
-    public static void SelectionSort(int[] nums) {
+    void SelectionSort(int[] nums) {
         int n = nums.Length;
         // 外循环：未排序区间为 [i, n-1]
         for (int i = 0; i < n - 1; i++) {
@@ -25,7 +25,7 @@ public class selection_sort {
 
     [Test]
     public void Test() {
-        int[] nums = { 4, 1, 3, 1, 5, 2 };
+        int[] nums = [4, 1, 3, 1, 5, 2];
         SelectionSort(nums);
         Console.WriteLine("选择排序完成后 nums = " + string.Join(" ", nums));
     }

codes/csharp/chapter_stack_and_queue/array_deque.cs

@@ -8,18 +8,18 @@ namespace hello_algo.chapter_stack_and_queue;
 
 /* 基于环形数组实现的双向队列 */
 public class ArrayDeque {
-    private readonly int[] nums;  // 用于存储双向队列元素的数组
+    int[] nums;  // 用于存储双向队列元素的数组
-    private int front;   // 队首指针，指向队首元素
+    int front;   // 队首指针，指向队首元素
-    private int queSize; // 双向队列长度
+    int queSize; // 双向队列长度
 
     /* 构造方法 */
     public ArrayDeque(int capacity) {
-        this.nums = new int[capacity];
+        nums = new int[capacity];
         front = queSize = 0;
     }
 
     /* 获取双向队列的容量 */
-    public int Capacity() {
+    int Capacity() {
         return nums.Length;
     }
 
@@ -34,7 +34,7 @@ public class ArrayDeque {
     }
 
     /* 计算环形数组索引 */
-    private int Index(int i) {
+    int Index(int i) {
         // 通过取余操作实现数组首尾相连
         // 当 i 越过数组尾部后，回到头部
         // 当 i 越过数组头部后，回到尾部

codes/csharp/chapter_stack_and_queue/array_queue.cs

@@ -8,9 +8,9 @@ namespace hello_algo.chapter_stack_and_queue;
 
 /* 基于环形数组实现的队列 */
 class ArrayQueue {
-    private readonly int[] nums;  // 用于存储队列元素的数组
+    int[] nums;  // 用于存储队列元素的数组
-    private int front;   // 队首指针，指向队首元素
+    int front;   // 队首指针，指向队首元素
-    private int queSize; // 队列长度
+    int queSize; // 队列长度
 
     public ArrayQueue(int capacity) {
         nums = new int[capacity];
@@ -18,7 +18,7 @@ class ArrayQueue {
     }
 
     /* 获取队列的容量 */
-    public int Capacity() {
+    int Capacity() {
         return nums.Length;
     }
 

codes/csharp/chapter_stack_and_queue/array_stack.cs

@@ -8,10 +8,10 @@ namespace hello_algo.chapter_stack_and_queue;
 
 /* 基于数组实现的栈 */
 class ArrayStack {
-    private readonly List<int> stack;
+    List<int> stack;
     public ArrayStack() {
         // 初始化列表（动态数组）
-        stack = new();
+        stack = [];
     }
 
     /* 获取栈的长度 */
@@ -47,7 +47,7 @@ class ArrayStack {
 
     /* 将 List 转化为 Array 并返回 */
     public int[] ToArray() {
-        return stack.ToArray();
+        return [.. stack];
     }
 }
 

codes/csharp/chapter_stack_and_queue/linkedlist_deque.cs

@@ -7,22 +7,16 @@
 namespace hello_algo.chapter_stack_and_queue;
 
 /* 双向链表节点 */
-public class ListNode {
+public class ListNode(int val) {
-    public int val;       // 节点值
+    public int val = val;       // 节点值
-    public ListNode? next; // 后继节点引用
+    public ListNode? next = null; // 后继节点引用
-    public ListNode? prev; // 前驱节点引用
+    public ListNode? prev = null; // 前驱节点引用
-
-    public ListNode(int val) {
-        this.val = val;
-        prev = null;
-        next = null;
-    }
 }
 
 /* 基于双向链表实现的双向队列 */
 public class LinkedListDeque {
-    private ListNode? front, rear; // 头节点 front, 尾节点 rear
+    ListNode? front, rear; // 头节点 front, 尾节点 rear
-    private int queSize = 0;      // 双向队列的长度
+    int queSize = 0;      // 双向队列的长度
 
     public LinkedListDeque() {
         front = null;
@@ -40,7 +34,7 @@ public class LinkedListDeque {
     }
 
     /* 入队操作 */
-    private void Push(int num, bool isFront) {
+    void Push(int num, bool isFront) {
         ListNode node = new(num);
         // 若链表为空，则令 front, rear 都指向 node
         if (IsEmpty()) {
@@ -50,14 +44,14 @@ public class LinkedListDeque {
         // 队首入队操作
         else if (isFront) {
             // 将 node 添加至链表头部
-            front.prev = node;
+            front!.prev = node;
             node.next = front;
             front = node; // 更新头节点                           
         }
         // 队尾入队操作
         else {
             // 将 node 添加至链表尾部
-            rear.next = node;
+            rear!.next = node;
             node.prev = rear;
             rear = node;  // 更新尾节点
         }
@@ -76,7 +70,7 @@ public class LinkedListDeque {
     }
 
     /* 出队操作 */
-    private int? Pop(bool isFront) {
+    int? Pop(bool isFront) {
         if (IsEmpty())
             throw new Exception();
         int? val;
@@ -87,7 +81,7 @@ public class LinkedListDeque {
             ListNode? fNext = front?.next;
             if (fNext != null) {
                 fNext.prev = null;
-                front.next = null;
+                front!.next = null;
             }
             front = fNext;   // 更新头节点
         }
@@ -98,7 +92,7 @@ public class LinkedListDeque {
             ListNode? rPrev = rear?.prev;
             if (rPrev != null) {
                 rPrev.next = null;
-                rear.prev = null;
+                rear!.prev = null;
             }
             rear = rPrev;    // 更新尾节点
         }

codes/csharp/chapter_stack_and_queue/linkedlist_queue.cs

@@ -8,8 +8,8 @@ namespace hello_algo.chapter_stack_and_queue;
 
 /* 基于链表实现的队列 */
 class LinkedListQueue {
-    private ListNode? front, rear;  // 头节点 front ，尾节点 rear 
+    ListNode? front, rear;  // 头节点 front ，尾节点 rear 
-    private int queSize = 0;
+    int queSize = 0;
 
     public LinkedListQueue() {
         front = null;
@@ -55,18 +55,18 @@ class LinkedListQueue {
     public int Peek() {
         if (IsEmpty())
             throw new Exception();
-        return front.val;
+        return front!.val;
     }
 
     /* 将链表转化为 Array 并返回 */
     public int[] ToArray() {
         if (front == null)
-            return Array.Empty<int>();
+            return [];
 
-        ListNode node = front;
+        ListNode? node = front;
         int[] res = new int[Size()];
         for (int i = 0; i < res.Length; i++) {
-            res[i] = node.val;
+            res[i] = node!.val;
             node = node.next;
         }
         return res;

codes/csharp/chapter_stack_and_queue/linkedlist_stack.cs

@@ -8,8 +8,8 @@ namespace hello_algo.chapter_stack_and_queue;
 
 /* 基于链表实现的栈 */
 class LinkedListStack {
-    private ListNode? stackPeek;  // 将头节点作为栈顶
+    ListNode? stackPeek;  // 将头节点作为栈顶
-    private int stkSize = 0;   // 栈的长度
+    int stkSize = 0;   // 栈的长度
 
     public LinkedListStack() {
         stackPeek = null;
@@ -37,7 +37,7 @@ class LinkedListStack {
     /* 出栈 */
     public int Pop() {
         int num = Peek();
-        stackPeek = stackPeek.next;
+        stackPeek = stackPeek!.next;
         stkSize--;
         return num;
     }
@@ -46,18 +46,18 @@ class LinkedListStack {
     public int Peek() {
         if (IsEmpty())
             throw new Exception();
-        return stackPeek.val;
+        return stackPeek!.val;
     }
 
     /* 将 List 转化为 Array 并返回 */
     public int[] ToArray() {
         if (stackPeek == null)
-            return Array.Empty<int>();
+            return [];
 
-        ListNode node = stackPeek;
+        ListNode? node = stackPeek;
         int[] res = new int[Size()];
         for (int i = res.Length - 1; i >= 0; i--) {
-            res[i] = node.val;
+            res[i] = node!.val;
             node = node.next;
         }
         return res;

codes/csharp/chapter_tree/array_binary_tree.cs

@@ -7,13 +7,8 @@
 namespace hello_algo.chapter_tree;
 
 /* 数组表示下的二叉树类 */
-public class ArrayBinaryTree {
+public class ArrayBinaryTree(List<int?> arr) {
-    private readonly List<int?> tree;
+    List<int?> tree = new(arr);
-
-    /* 构造方法 */
-    public ArrayBinaryTree(List<int?> arr) {
-        tree = new List<int?>(arr);
-    }
 
     /* 节点数量 */
     public int Size() {
@@ -45,50 +40,50 @@ public class ArrayBinaryTree {
 
     /* 层序遍历 */
     public List<int> LevelOrder() {
-        List<int> res = new();
+        List<int> res = [];
         // 直接遍历数组
         for (int i = 0; i < Size(); i++) {
             if (Val(i).HasValue)
-                res.Add(Val(i).Value);
+                res.Add(Val(i)!.Value);
         }
         return res;
     }
 
     /* 深度优先遍历 */
-    private void DFS(int i, string order, List<int> res) {
+    void DFS(int i, string order, List<int> res) {
         // 若为空位，则返回
         if (!Val(i).HasValue)
             return;
         // 前序遍历
         if (order == "pre")
-            res.Add(Val(i).Value);
+            res.Add(Val(i)!.Value);
         DFS(Left(i), order, res);
         // 中序遍历
         if (order == "in")
-            res.Add(Val(i).Value);
+            res.Add(Val(i)!.Value);
         DFS(Right(i), order, res);
         // 后序遍历
         if (order == "post")
-            res.Add(Val(i).Value);
+            res.Add(Val(i)!.Value);
     }
 
     /* 前序遍历 */
     public List<int> PreOrder() {
-        List<int> res = new();
+        List<int> res = [];
         DFS(0, "pre", res);
         return res;
     }
 
     /* 中序遍历 */
     public List<int> InOrder() {
-        List<int> res = new();
+        List<int> res = [];
         DFS(0, "in", res);
         return res;
     }
 
     /* 后序遍历 */
     public List<int> PostOrder() {
-        List<int> res = new();
+        List<int> res = [];
         DFS(0, "post", res);
         return res;
     }
@@ -99,9 +94,9 @@ public class array_binary_tree {
     public void Test() {
         // 初始化二叉树
         // 这里借助了一个从数组直接生成二叉树的函数
-        List<int?> arr = new() { 1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15 };
+        List<int?> arr = [1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15];
 
-        TreeNode root = TreeNode.ListToTree(arr);
+        TreeNode? root = TreeNode.ListToTree(arr);
         Console.WriteLine("\n初始化二叉树\n");
         Console.WriteLine("二叉树的数组表示：");
         Console.WriteLine(arr.PrintList());

codes/csharp/chapter_tree/avl_tree.cs

@@ -11,13 +11,13 @@ class AVLTree {
     public TreeNode? root; // 根节点
 
     /* 获取节点高度 */
-    public int Height(TreeNode? node) {
+    int Height(TreeNode? node) {
         // 空节点高度为 -1 ，叶节点高度为 0
         return node == null ? -1 : node.height;
     }
 
     /* 更新节点高度 */
-    private void UpdateHeight(TreeNode node) {
+    void UpdateHeight(TreeNode node) {
         // 节点高度等于最高子树高度 + 1
         node.height = Math.Max(Height(node.left), Height(node.right)) + 1;
     }
@@ -32,7 +32,7 @@ class AVLTree {
 
     /* 右旋操作 */
     TreeNode? RightRotate(TreeNode? node) {
-        TreeNode? child = node.left;
+        TreeNode? child = node?.left;
         TreeNode? grandChild = child?.right;
         // 以 child 为原点，将 node 向右旋转
         child.right = node;
@@ -46,7 +46,7 @@ class AVLTree {
 
     /* 左旋操作 */
     TreeNode? LeftRotate(TreeNode? node) {
-        TreeNode? child = node.right;
+        TreeNode? child = node?.right;
         TreeNode? grandChild = child?.left;
         // 以 child 为原点，将 node 向左旋转
         child.left = node;
@@ -64,23 +64,23 @@ class AVLTree {
         int balanceFactorInt = BalanceFactor(node);
         // 左偏树
         if (balanceFactorInt > 1) {
-            if (BalanceFactor(node.left) >= 0) {
+            if (BalanceFactor(node?.left) >= 0) {
                 // 右旋
                 return RightRotate(node);
             } else {
                 // 先左旋后右旋
-                node.left = LeftRotate(node?.left);
+                node!.left = LeftRotate(node!.left);
                 return RightRotate(node);
             }
         }
         // 右偏树
         if (balanceFactorInt < -1) {
-            if (BalanceFactor(node.right) <= 0) {
+            if (BalanceFactor(node?.right) <= 0) {
                 // 左旋
                 return LeftRotate(node);
             } else {
                 // 先右旋后左旋
-                node.right = RightRotate(node?.right);
+                node!.right = RightRotate(node!.right);
                 return LeftRotate(node);
             }
         }
@@ -94,7 +94,7 @@ class AVLTree {
     }
 
     /* 递归插入节点（辅助方法） */
-    private TreeNode? InsertHelper(TreeNode? node, int val) {
+    TreeNode? InsertHelper(TreeNode? node, int val) {
         if (node == null) return new TreeNode(val);
         /* 1. 查找插入位置，并插入节点 */
         if (val < node.val)
@@ -116,7 +116,7 @@ class AVLTree {
     }
 
     /* 递归删除节点（辅助方法） */
-    private TreeNode? RemoveHelper(TreeNode? node, int val) {
+    TreeNode? RemoveHelper(TreeNode? node, int val) {
         if (node == null) return null;
         /* 1. 查找节点，并删除之 */
         if (val < node.val)
@@ -138,7 +138,7 @@ class AVLTree {
                 while (temp.left != null) {
                     temp = temp.left;
                 }
-                node.right = RemoveHelper(node.right, temp.val);
+                node.right = RemoveHelper(node.right, temp.val!.Value);
                 node.val = temp.val;
             }
         }

codes/csharp/chapter_tree/binary_search_tree.cs

@@ -99,7 +99,7 @@ class BinarySearchTree {
             TreeNode? child = cur.left ?? cur.right;
             // 删除节点 cur
             if (cur != root) {
-                if (pre.left == cur)
+                if (pre!.left == cur)
                     pre.left = child;
                 else
                     pre.right = child;
@@ -116,7 +116,7 @@ class BinarySearchTree {
                 tmp = tmp.left;
             }
             // 递归删除节点 tmp
-            Remove(tmp.val);
+            Remove(tmp.val!.Value);
             // 用 tmp 覆盖 cur
             cur.val = tmp.val;
         }
@@ -129,7 +129,7 @@ public class binary_search_tree {
         /* 初始化二叉搜索树 */
         BinarySearchTree bst = new();
         // 请注意，不同的插入顺序会生成不同的二叉树，该序列可以生成一个完美二叉树
-        int[] nums = { 8, 4, 12, 2, 6, 10, 14, 1, 3, 5, 7, 9, 11, 13, 15 };
+        int[] nums = [8, 4, 12, 2, 6, 10, 14, 1, 3, 5, 7, 9, 11, 13, 15];
         foreach (int num in nums) {
             bst.Insert(num);
         }
@@ -139,7 +139,7 @@ public class binary_search_tree {
 
         /* 查找节点 */
         TreeNode? node = bst.Search(7);
-        Console.WriteLine("\n查找到的节点对象为 " + node + "，节点值 = " + node.val);
+        Console.WriteLine("\n查找到的节点对象为 " + node + "，节点值 = " + node?.val);
 
         /* 插入节点 */
         bst.Insert(16);

codes/csharp/chapter_tree/binary_tree_bfs.cs

@@ -9,15 +9,15 @@ namespace hello_algo.chapter_tree;
 public class binary_tree_bfs {
 
     /* 层序遍历 */
-    public List<int> LevelOrder(TreeNode root) {
+    List<int> LevelOrder(TreeNode root) {
         // 初始化队列，加入根节点
         Queue<TreeNode> queue = new();
         queue.Enqueue(root);
         // 初始化一个列表，用于保存遍历序列
-        List<int> list = new();
+        List<int> list = [];
         while (queue.Count != 0) {
             TreeNode node = queue.Dequeue(); // 队列出队
-            list.Add(node.val);              // 保存节点值
+            list.Add(node.val!.Value);       // 保存节点值
             if (node.left != null)
                 queue.Enqueue(node.left);    // 左子节点入队
             if (node.right != null)
@@ -30,11 +30,11 @@ public class binary_tree_bfs {
     public void Test() {
         /* 初始化二叉树 */
         // 这里借助了一个从数组直接生成二叉树的函数
-        TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 2, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树\n");
         PrintUtil.PrintTree(root);
 
-        List<int> list = LevelOrder(root);
+        List<int> list = LevelOrder(root!);
         Console.WriteLine("\n层序遍历的节点打印序列 = " + string.Join(",", list));
     }
 }

codes/csharp/chapter_tree/binary_tree_dfs.cs

@@ -7,13 +7,13 @@
 namespace hello_algo.chapter_tree;
 
 public class binary_tree_dfs {
-    readonly List<int> list = new();
+    List<int> list = [];
 
     /* 前序遍历 */
     void PreOrder(TreeNode? root) {
         if (root == null) return;
         // 访问优先级：根节点 -> 左子树 -> 右子树
-        list.Add(root.val);
+        list.Add(root.val!.Value);
         PreOrder(root.left);
         PreOrder(root.right);
     }
@@ -23,7 +23,7 @@ public class binary_tree_dfs {
         if (root == null) return;
         // 访问优先级：左子树 -> 根节点 -> 右子树
         InOrder(root.left);
-        list.Add(root.val);
+        list.Add(root.val!.Value);
         InOrder(root.right);
     }
 
@@ -33,14 +33,14 @@ public class binary_tree_dfs {
         // 访问优先级：左子树 -> 右子树 -> 根节点
         PostOrder(root.left);
         PostOrder(root.right);
-        list.Add(root.val);
+        list.Add(root.val!.Value);
     }
 
     [Test]
     public void Test() {
         /* 初始化二叉树 */
         // 这里借助了一个从数组直接生成二叉树的函数
-        TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });
+        TreeNode? root = TreeNode.ListToTree([1, 2, 3, 4, 5, 6, 7]);
         Console.WriteLine("\n初始化二叉树\n");
         PrintUtil.PrintTree(root);
 

codes/csharp/hello-algo.csproj

@@ -2,17 +2,20 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <RootNamespace>hello_algo</RootNamespace>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.4.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageReference Include="NUnit" Version="3.13.3" />
+    <PackageReference Include="NUnit" Version="3.14.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.3.1" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
-    <PackageReference Include="coverlet.collector" Version="3.1.0" />
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
   </ItemGroup>
 
 </Project>

codes/csharp/utils/ListNode.cs

@@ -5,14 +5,10 @@
 namespace hello_algo.utils;
 
 /* Definition for a singly-linked list node */
-public class ListNode {
+public class ListNode(int x) {
-    public int val;
+    public int val = x;
     public ListNode? next;
 
-    public ListNode(int x) {
-        val = x;
-    }
-
     /* Generate a linked list with an array */
     public static ListNode? ArrToLinkedList(int[] arr) {
         ListNode dum = new(0);
@@ -33,7 +29,7 @@ public class ListNode {
     }
 
     public override string? ToString() {
-        List<string> list = new();
+        List<string> list = [];
         var head = this;
         while (head != null) {
             list.Add(head.val.ToString());

codes/csharp/utils/PrintUtil.cs

@@ -6,14 +6,9 @@
 
 namespace hello_algo.utils;
 
-public class Trunk {
+public class Trunk(Trunk? prev, string str) {
-    public Trunk? prev;
+    public Trunk? prev = prev;
-    public string str;
+    public string str = str;
-
-    public Trunk(Trunk? prev, string str) {
-        this.prev = prev;
-        this.str = str;
-    }
 };
 
 public static class PrintUtil {
@@ -45,8 +40,8 @@ public static class PrintUtil {
     }
 
     /* Print a linked list */
-    public static void PrintLinkedList(ListNode head) {
+    public static void PrintLinkedList(ListNode? head) {
-        List<string> list = new();
+        List<string> list = [];
         while (head != null) {
             list.Add(head.val.ToString());
             head = head.next;
@@ -115,10 +110,10 @@ public static class PrintUtil {
     /* Print a heap */
     public static void PrintHeap(Queue<int> queue) {
         Console.Write("堆的数组表示：");
-        List<int> list = queue.ToList();
+        List<int> list = [.. queue];
         Console.WriteLine(string.Join(',', list));
         Console.WriteLine("堆的树状表示：");
-        TreeNode tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
+        TreeNode? tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
         PrintTree(tree);
     }
 
@@ -126,13 +121,13 @@ public static class PrintUtil {
     public static void PrintHeap(PriorityQueue<int, int> queue) {
         var newQueue = new PriorityQueue<int, int>(queue.UnorderedItems, queue.Comparer);
         Console.Write("堆的数组表示：");
-        List<int> list = new();
+        List<int> list = [];
         while (newQueue.TryDequeue(out int element, out _)) {
             list.Add(element);
         }
         Console.WriteLine("堆的树状表示：");
         Console.WriteLine(string.Join(',', list.ToList()));
-        TreeNode tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
+        TreeNode? tree = TreeNode.ListToTree(list.Cast<int?>().ToList());
         PrintTree(tree);
     }
 }

codes/csharp/utils/TreeNode.cs

@@ -7,17 +7,12 @@
 namespace hello_algo.utils;
 
 /* 二叉树节点类 */
-public class TreeNode {
+public class TreeNode(int? x) {
-    public int val;        // 节点值
+    public int? val = x;    // 节点值
-    public int height;     // 节点高度
+    public int height;      // 节点高度
     public TreeNode? left;  // 左子节点引用
     public TreeNode? right; // 右子节点引用
 
-    /* 构造方法 */
-    public TreeNode(int x) {
-        val = x;
-    }
-
     // 序列化编码规则请参考：
     // https://www.hello-algo.com/chapter_tree/array_representation_of_tree/
     // 二叉树的数组表示：
@@ -35,11 +30,11 @@ public class TreeNode {
     //             \——— 8
 
     /* 将列表反序列化为二叉树：递归 */
-    private static TreeNode? ListToTreeDFS(List<int?> arr, int i) {
+    static TreeNode? ListToTreeDFS(List<int?> arr, int i) {
         if (i < 0 || i >= arr.Count || !arr[i].HasValue) {
             return null;
         }
-        TreeNode root = new(arr[i].Value) {
+        TreeNode root = new(arr[i]) {
             left = ListToTreeDFS(arr, 2 * i + 1),
             right = ListToTreeDFS(arr, 2 * i + 2)
         };
@@ -52,7 +47,7 @@ public class TreeNode {
     }
 
     /* 将二叉树序列化为列表：递归 */
-    private static void TreeToListDFS(TreeNode? root, int i, List<int?> res) {
+    static void TreeToListDFS(TreeNode? root, int i, List<int?> res) {
         if (root == null)
             return;
         while (i >= res.Count) {
@@ -65,7 +60,7 @@ public class TreeNode {
 
     /* 将二叉树序列化为列表 */
     public static List<int?> TreeToList(TreeNode root) {
-        List<int?> res = new();
+        List<int?> res = [];
         TreeToListDFS(root, 0, res);
         return res;
     }

codes/csharp/utils/Vertex.cs

@@ -7,11 +7,8 @@
 namespace hello_algo.utils;
 
 /* 顶点类 */
-public class Vertex {
+public class Vertex(int val) {
-    public int val;
+    public int val = val;
-    public Vertex(int val) {
-        this.val = val;
-    }
 
     /* 输入值列表 vals ，返回顶点列表 vets */
     public static Vertex[] ValsToVets(int[] vals) {
@@ -24,7 +21,7 @@ public class Vertex {
 
     /* 输入顶点列表 vets ，返回值列表 vals */
     public static List<int> VetsToVals(List<Vertex> vets) {
-        List<int> vals = new();
+        List<int> vals = [];
         foreach (Vertex vet in vets) {
             vals.Add(vet.val);
         }

docs/chapter_appendix/installation.md

@@ -35,7 +35,7 @@
 
 ### C# 环境
 
-1. 下载并安装 [.Net 6.0](https://dotnet.microsoft.com/en-us/download) 。
+1. 下载并安装 [.Net 8.0](https://dotnet.microsoft.com/en-us/download) 。
 2. 在 VSCode 的插件市场中搜索 `C# Dev Kit` ，安装 C# Dev Kit （[配置教程](https://code.visualstudio.com/docs/csharp/get-started)）。
 3. 也可使用 Visual Studio（[安装教程](https://learn.microsoft.com/zh-cn/visualstudio/install/install-visual-studio?view=vs-2022)）。
 

docs/chapter_array_and_linkedlist/array.md

@@ -43,7 +43,7 @@
     ```csharp title="array.cs"
     /* 初始化数组 */
     int[] arr = new int[5]; // { 0, 0, 0, 0, 0 }
-    int[] nums = { 1, 3, 2, 5, 4 };
+    int[] nums = [1, 3, 2, 5, 4];
     ```
 
 === "Go"

docs/chapter_array_and_linkedlist/linked_list.md

@@ -52,10 +52,9 @@
 
     ```csharp title=""
     /* 链表节点类 */
-    class ListNode {
+    class ListNode(int x) {  //构造函数
-        int val;         // 节点值
+        int val = x;         // 节点值
-        ListNode next;   // 指向下一节点的引用
+        ListNode? next;      // 指向下一节点的引用
-        ListNode(int x) => val = x;  //构造函数
     }
     ```
 
@@ -495,11 +494,10 @@
 
     ```csharp title=""
     /* 双向链表节点类 */
-    class ListNode {
+    class ListNode(int x) {  // 构造函数
-        int val;        // 节点值
+        int val = x;    // 节点值
         ListNode next;  // 指向后继节点的引用
         ListNode prev;  // 指向前驱节点的引用
-        ListNode(int x) => val = x;  // 构造函数
     }
     ```
 

docs/chapter_array_and_linkedlist/list.md

@@ -54,10 +54,10 @@
     ```csharp title="list.cs"
     /* 初始化列表 */
     // 无初始值
-    List<int> nums1 = new();
+    List<int> nums1 = [];
     // 有初始值
-    int[] numbers = new int[] { 1, 3, 2, 5, 4 };
+    int[] numbers = [1, 3, 2, 5, 4];
-    List<int> nums = numbers.ToList();
+    List<int> nums = [.. numbers];
     ```
 
 === "Go"
@@ -700,7 +700,7 @@
 
     ```csharp title="list.cs"
     /* 拼接两个列表 */
-    List<int> nums1 = new() { 6, 8, 7, 10, 9 };
+    List<int> nums1 = [6, 8, 7, 10, 9];
     nums.AddRange(nums1);  // 将列表 nums1 拼接到 nums 之后
     ```
 

docs/chapter_computational_complexity/space_complexity.md

@@ -98,10 +98,9 @@
 
     ```csharp title=""
     /* 类 */
-    class Node {
+    class Node(int x) {
-        int val;
+        int val = x;
         Node next;
-        Node(int x) { val = x; }
     }
 
     /* 函数 */
@@ -113,7 +112,7 @@
     int Algorithm(int n) {        // 输入数据
         const int a = 0;          // 暂存数据（常量）
         int b = 0;                // 暂存数据（变量）
-        Node node = new(0);  // 暂存数据（对象）
+        Node node = new(0);       // 暂存数据（对象）
         int c = Function();       // 栈帧空间（调用函数）
         return a + b + c;         // 输出数据
     }

docs/chapter_hashing/hash_algorithm.md

@@ -211,7 +211,7 @@ $$
     int hashStr = str.GetHashCode();
     // 字符串 Hello 算法 的哈希值为 -586107568;
 
-    object[] arr = { 12836, "小哈" };
+    object[] arr = [12836, "小哈"];
     int hashTup = arr.GetHashCode();
     // 数组 [12836, 小哈] 的哈希值为 42931033;
 

docs/chapter_heap/heap.md

@@ -187,7 +187,7 @@
     bool isEmpty = maxHeap.Count == 0;
 
     /* 输入列表并建堆 */
-    minHeap = new PriorityQueue<int, int>(new List<(int, int)> { (1, 1), (3, 3), (2, 2), (5, 5), (4, 4), });
+    minHeap = new PriorityQueue<int, int>([(1, 1), (3, 3), (2, 2), (5, 5), (4, 4)]);
     ```
 
 === "Go"

docs/chapter_tree/array_representation_of_tree.md

@@ -53,7 +53,7 @@
     ```csharp title=""
     /* 二叉树的数组表示 */
     // 使用 int? 可空类型 ，就可以使用 null 来标记空位
-    int?[] tree = { 1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15 };
+    int?[] tree = [1, 2, 3, 4, null, 6, 7, 8, 9, null, null, 12, null, null, 15];
     ```
 
 === "Go"

docs/chapter_tree/avl_tree.md

@@ -63,12 +63,11 @@ AVL 树既是二叉搜索树也是平衡二叉树，同时满足这两类二叉
 
     ```csharp title=""
     /* AVL 树节点类 */
-    class TreeNode {
+    class TreeNode(int? x) {
-        public int val;          // 节点值
+        public int? val = x;    // 节点值
-        public int height;       // 节点高度
+        public int height;      // 节点高度
-        public TreeNode? left;   // 左子节点
+        public TreeNode? left;  // 左子节点引用
-        public TreeNode? right;  // 右子节点
+        public TreeNode? right; // 右子节点引用
-        public TreeNode(int x) { val = x; }
     }
     ```
 

docs/chapter_tree/binary_tree.md

@@ -41,11 +41,10 @@
 
     ```csharp title=""
     /* 二叉树节点类 */
-    class TreeNode {
+    class TreeNode(int? x) {
-        int val;          // 节点值
+        public int? val = x;    // 节点值
-        TreeNode? left;   // 左子节点引用
+        public TreeNode? left;  // 左子节点引用
-        TreeNode? right;  // 右子节点引用
+        public TreeNode? right; // 右子节点引用
-        TreeNode(int x) { val = x; }
     }
     ```