Many bug fixes and improvements (#1270)

* Add Ruby and Kotlin icons
Add the avatar of @curtishd

* Update README

* Synchronize zh-hant and zh versions.

* Translate the pythontutor blocks to traditional Chinese

* Fix en/mkdocs.yml

* Update the landing page of the en version.

* Fix the Dockerfile

* Refine the en landingpage

* Fix en landing page

* Reset the README.md

zh-hant/codes/kotlin/chapter_backtracking/n_queens.kt

@@ -10,17 +10,17 @@ package chapter_backtracking.n_queens
 fun backtrack(
     row: Int,
     n: Int,
-    state: List<MutableList<String>>,
-    res: MutableList<List<List<String>>?>,
+    state: MutableList<MutableList<String>>,
+    res: MutableList<MutableList<MutableList<String>>?>,
     cols: BooleanArray,
     diags1: BooleanArray,
     diags2: BooleanArray
 ) {
     // 當放置完所有行時，記錄解
     if (row == n) {
-        val copyState: MutableList<List<String>> = ArrayList()
+        val copyState = mutableListOf<MutableList<String>>()
         for (sRow in state) {
-            copyState.add(ArrayList(sRow))
+            copyState.add(sRow.toMutableList())
         }
         res.add(copyState)
         return
@@ -49,11 +49,11 @@ fun backtrack(
 }
 
 /* 求解 n 皇后 */
-fun nQueens(n: Int): List<List<List<String>>?> {
+fun nQueens(n: Int): MutableList<MutableList<MutableList<String>>?> {
     // 初始化 n*n 大小的棋盤，其中 'Q' 代表皇后，'#' 代表空位
-    val state: MutableList<MutableList<String>> = ArrayList()
+    val state = mutableListOf<MutableList<String>>()
     for (i in 0..<n) {
-        val row: MutableList<String> = ArrayList()
+        val row = mutableListOf<String>()
         for (j in 0..<n) {
             row.add("#")
         }
@@ -62,7 +62,7 @@ fun nQueens(n: Int): List<List<List<String>>?> {
     val cols = BooleanArray(n) // 記錄列是否有皇后
     val diags1 = BooleanArray(2 * n - 1) // 記錄主對角線上是否有皇后
     val diags2 = BooleanArray(2 * n - 1) // 記錄次對角線上是否有皇后
-    val res: MutableList<List<List<String>>?> = ArrayList()
+    val res = mutableListOf<MutableList<MutableList<String>>?>()
 
     backtrack(0, n, state, res, cols, diags1, diags2)
 
@@ -72,7 +72,7 @@ fun nQueens(n: Int): List<List<List<String>>?> {
 /* Driver Code */
 fun main() {
     val n = 4
-    val res: List<List<List<String?>?>?> = nQueens(n)
+    val res = nQueens(n)
 
     println("輸入棋盤長寬為 $n")
     println("皇后放置方案共有 ${res.size} 種")

zh-hant/codes/kotlin/chapter_backtracking/permutations_i.kt

@@ -11,11 +11,11 @@ fun backtrack(
     state: MutableList<Int>,
     choices: IntArray,
     selected: BooleanArray,
-    res: MutableList<List<Int>?>
+    res: MutableList<MutableList<Int>?>
 ) {
     // 當狀態長度等於元素數量時，記錄解
     if (state.size == choices.size) {
-        res.add(ArrayList(state))
+        res.add(state.toMutableList())
         return
     }
     // 走訪所有選擇
@@ -36,9 +36,9 @@ fun backtrack(
 }
 
 /* 全排列 I */
-fun permutationsI(nums: IntArray): List<List<Int>?> {
-    val res: MutableList<List<Int>?> = ArrayList()
-    backtrack(ArrayList(), nums, BooleanArray(nums.size), res)
+fun permutationsI(nums: IntArray): MutableList<MutableList<Int>?> {
+    val res = mutableListOf<MutableList<Int>?>()
+    backtrack(mutableListOf(), nums, BooleanArray(nums.size), res)
     return res
 }
 

zh-hant/codes/kotlin/chapter_backtracking/permutations_ii.kt

@@ -15,11 +15,11 @@ fun backtrack(
 ) {
     // 當狀態長度等於元素數量時，記錄解
     if (state.size == choices.size) {
-        res.add(ArrayList(state))
+        res.add(state.toMutableList())
         return
     }
     // 走訪所有選擇
-    val duplicated: MutableSet<Int> = HashSet()
+    val duplicated = HashSet<Int>()
     for (i in choices.indices) {
         val choice = choices[i]
         // 剪枝：不允許重複選擇元素 且 不允許重複選擇相等元素
@@ -39,15 +39,14 @@ fun backtrack(
 
 /* 全排列 II */
 fun permutationsII(nums: IntArray): MutableList<MutableList<Int>?> {
-    val res: MutableList<MutableList<Int>?> = ArrayList()
-    backtrack(ArrayList(), nums, BooleanArray(nums.size), res)
+    val res = mutableListOf<MutableList<Int>?>()
+    backtrack(mutableListOf(), nums, BooleanArray(nums.size), res)
     return res
 }
 
 /* Driver Code */
 fun main() {
     val nums = intArrayOf(1, 2, 2)
-
     val res = permutationsII(nums)
 
     println("輸入陣列 nums = ${nums.contentToString()}")

zh-hant/codes/kotlin/chapter_backtracking/preorder_traversal_i_compact.kt

@@ -16,7 +16,7 @@ fun preOrder(root: TreeNode?) {
     if (root == null) {
         return
     }
-    if (root.value == 7) {
+    if (root._val == 7) {
         // 記錄解
         res!!.add(root)
     }
@@ -31,13 +31,13 @@ fun main() {
     printTree(root)
 
     // 前序走訪
-    res = ArrayList()
+    res = mutableListOf()
     preOrder(root)
 
     println("\n輸出所有值為 7 的節點")
-    val vals: MutableList<Int> = ArrayList()
-    for (node in res as ArrayList<TreeNode>) {
-        vals.add(node.value)
+    val vals = mutableListOf<Int>()
+    for (node in res!!) {
+        vals.add(node._val)
     }
     println(vals)
 }

zh-hant/codes/kotlin/chapter_backtracking/preorder_traversal_ii_compact.kt

@@ -10,7 +10,7 @@ import utils.TreeNode
 import utils.printTree
 
 var path: MutableList<TreeNode>? = null
-var res: MutableList<List<TreeNode>>? = null
+var res: MutableList<MutableList<TreeNode>>? = null
 
 /* 前序走訪：例題二 */
 fun preOrder(root: TreeNode?) {
@@ -19,9 +19,9 @@ fun preOrder(root: TreeNode?) {
     }
     // 嘗試
     path!!.add(root)
-    if (root.value == 7) {
+    if (root._val == 7) {
         // 記錄解
-        res!!.add(ArrayList(path!!))
+        res!!.add(path!!.toMutableList())
     }
     preOrder(root.left)
     preOrder(root.right)
@@ -36,16 +36,16 @@ fun main() {
     printTree(root)
 
     // 前序走訪
-    path = java.util.ArrayList<TreeNode>()
-    res = java.util.ArrayList<List<TreeNode>>()
+    path = mutableListOf()
+    res = mutableListOf()
     preOrder(root)
 
     println("\n輸出所有根節點到節點 7 的路徑")
-    for (path in res as ArrayList<List<TreeNode>>) {
-        val values: MutableList<Int> = ArrayList()
+    for (path in res!!) {
+        val _vals = mutableListOf<Int>()
         for (node in path) {
-            values.add(node.value)
+            _vals.add(node._val)
         }
-        println(values)
+        println(_vals)
     }
 }

zh-hant/codes/kotlin/chapter_backtracking/preorder_traversal_iii_compact.kt

@@ -10,19 +10,19 @@ import utils.TreeNode
 import utils.printTree
 
 var path: MutableList<TreeNode>? = null
-var res: MutableList<List<TreeNode>>? = null
+var res: MutableList<MutableList<TreeNode>>? = null
 
 /* 前序走訪：例題三 */
 fun preOrder(root: TreeNode?) {
     // 剪枝
-    if (root == null || root.value == 3) {
+    if (root == null || root._val == 3) {
         return
     }
     // 嘗試
     path!!.add(root)
-    if (root.value == 7) {
+    if (root._val == 7) {
         // 記錄解
-        res!!.add(ArrayList(path!!))
+        res!!.add(path!!.toMutableList())
     }
     preOrder(root.left)
     preOrder(root.right)
@@ -37,16 +37,16 @@ fun main() {
     printTree(root)
 
     // 前序走訪
-    path = ArrayList()
-    res = ArrayList()
+    path = mutableListOf()
+    res = mutableListOf()
     preOrder(root)
 
     println("\n輸出所有根節點到節點 7 的路徑，路徑中不包含值為 3 的節點")
-    for (path in res as ArrayList<List<TreeNode>>) {
-        val values: MutableList<Int> = ArrayList()
+    for (path in res!!) {
+        val _vals = mutableListOf<Int>()
         for (node in path) {
-            values.add(node.value)
+            _vals.add(node._val)
         }
-        println(values)
+        println(_vals)
     }
 }

zh-hant/codes/kotlin/chapter_backtracking/preorder_traversal_iii_template.kt

@@ -8,21 +8,20 @@ package chapter_backtracking.preorder_traversal_iii_template
 
 import utils.TreeNode
 import utils.printTree
-import java.util.*
 
 /* 判斷當前狀態是否為解 */
-fun isSolution(state: List<TreeNode?>): Boolean {
-    return state.isNotEmpty() && state[state.size - 1]?.value == 7
+fun isSolution(state: MutableList<TreeNode?>): Boolean {
+    return state.isNotEmpty() && state[state.size - 1]?._val == 7
 }
 
 /* 記錄解 */
-fun recordSolution(state: MutableList<TreeNode?>?, res: MutableList<List<TreeNode?>?>) {
-    res.add(state?.let { ArrayList(it) })
+fun recordSolution(state: MutableList<TreeNode?>?, res: MutableList<MutableList<TreeNode?>?>) {
+    res.add(state!!.toMutableList())
 }
 
 /* 判斷在當前狀態下，該選擇是否合法 */
-fun isValid(state: List<TreeNode?>?, choice: TreeNode?): Boolean {
-    return choice != null && choice.value != 3
+fun isValid(state: MutableList<TreeNode?>?, choice: TreeNode?): Boolean {
+    return choice != null && choice._val != 3
 }
 
 /* 更新狀態 */
@@ -38,8 +37,8 @@ fun undoChoice(state: MutableList<TreeNode?>, choice: TreeNode?) {
 /* 回溯演算法：例題三 */
 fun backtrack(
     state: MutableList<TreeNode?>,
-    choices: List<TreeNode?>,
-    res: MutableList<List<TreeNode?>?>
+    choices: MutableList<TreeNode?>,
+    res: MutableList<MutableList<TreeNode?>?>
 ) {
     // 檢查是否為解
     if (isSolution(state)) {
@@ -53,7 +52,7 @@ fun backtrack(
             // 嘗試：做出選擇，更新狀態
             makeChoice(state, choice)
             // 進行下一輪選擇
-            backtrack(state, listOf(choice!!.left, choice.right), res)
+            backtrack(state, mutableListOf(choice!!.left, choice.right), res)
             // 回退：撤銷選擇，恢復到之前的狀態
             undoChoice(state, choice)
         }
@@ -67,15 +66,15 @@ fun main() {
     printTree(root)
 
     // 回溯演算法
-    val res: MutableList<List<TreeNode?>?> = ArrayList()
-    backtrack(ArrayList(), mutableListOf(root), res)
+    val res = mutableListOf<MutableList<TreeNode?>?>()
+    backtrack(mutableListOf(), mutableListOf(root), res)
 
     println("\n輸出所有根節點到節點 7 的路徑，要求路徑中不包含值為 3 的節點")
     for (path in res) {
-        val vals = ArrayList<Int>()
+        val vals = mutableListOf<Int>()
         for (node in path!!) {
             if (node != null) {
-                vals.add(node.value)
+                vals.add(node._val)
             }
         }
         println(vals)

zh-hant/codes/kotlin/chapter_backtracking/subset_sum_i.kt

@@ -6,19 +6,17 @@
 
 package chapter_backtracking.subset_sum_i
 
-import java.util.*
-
 /* 回溯演算法：子集和 I */
 fun backtrack(
     state: MutableList<Int>,
     target: Int,
     choices: IntArray,
     start: Int,
-    res: MutableList<List<Int>?>
+    res: MutableList<MutableList<Int>?>
 ) {
     // 子集和等於 target 時，記錄解
     if (target == 0) {
-        res.add(ArrayList(state))
+        res.add(state.toMutableList())
         return
     }
     // 走訪所有選擇
@@ -39,11 +37,11 @@ fun backtrack(
 }
 
 /* 求解子集和 I */
-fun subsetSumI(nums: IntArray, target: Int): List<List<Int>?> {
-    val state: MutableList<Int> = ArrayList() // 狀態（子集）
-    Arrays.sort(nums) // 對 nums 進行排序
+fun subsetSumI(nums: IntArray, target: Int): MutableList<MutableList<Int>?> {
+    val state = mutableListOf<Int>() // 狀態（子集）
+    nums.sort() // 對 nums 進行排序
     val start = 0 // 走訪起始點
-    val res: MutableList<List<Int>?> = ArrayList() // 結果串列（子集串列）
+    val res = mutableListOf<MutableList<Int>?>() // 結果串列（子集串列）
     backtrack(state, target, nums, start, res)
     return res
 }

zh-hant/codes/kotlin/chapter_backtracking/subset_sum_i_naive.kt

@@ -12,11 +12,11 @@ fun backtrack(
     target: Int,
     total: Int,
     choices: IntArray,
-    res: MutableList<List<Int>?>
+    res: MutableList<MutableList<Int>?>
 ) {
     // 子集和等於 target 時，記錄解
     if (total == target) {
-        res.add(ArrayList(state))
+        res.add(state.toMutableList())
         return
     }
     // 走訪所有選擇
@@ -35,10 +35,10 @@ fun backtrack(
 }
 
 /* 求解子集和 I（包含重複子集） */
-fun subsetSumINaive(nums: IntArray, target: Int): List<List<Int>?> {
-    val state: MutableList<Int> = ArrayList() // 狀態（子集）
+fun subsetSumINaive(nums: IntArray, target: Int): MutableList<MutableList<Int>?> {
+    val state = mutableListOf<Int>() // 狀態（子集）
     val total = 0 // 子集和
-    val res: MutableList<List<Int>?> = ArrayList() // 結果串列（子集串列）
+    val res = mutableListOf<MutableList<Int>?>() // 結果串列（子集串列）
     backtrack(state, target, total, nums, res)
     return res
 }
@@ -47,8 +47,7 @@ fun subsetSumINaive(nums: IntArray, target: Int): List<List<Int>?> {
 fun main() {
     val nums = intArrayOf(3, 4, 5)
     val target = 9
-
-    val res: List<List<Int>?> = subsetSumINaive(nums, target)
+    val res = subsetSumINaive(nums, target)
 
     println("輸入陣列 nums = ${nums.contentToString()}, target = $target")
     println("所有和等於 $target 的子集 res = $res")

zh-hant/codes/kotlin/chapter_backtracking/subset_sum_ii.kt

@@ -6,19 +6,17 @@
 
 package chapter_backtracking.subset_sum_ii
 
-import java.util.*
-
 /* 回溯演算法：子集和 II */
 fun backtrack(
     state: MutableList<Int>,
     target: Int,
     choices: IntArray,
     start: Int,
-    res: MutableList<List<Int>?>
+    res: MutableList<MutableList<Int>?>
 ) {
     // 子集和等於 target 時，記錄解
     if (target == 0) {
-        res.add(ArrayList(state))
+        res.add(state.toMutableList())
         return
     }
     // 走訪所有選擇
@@ -44,11 +42,11 @@ fun backtrack(
 }
 
 /* 求解子集和 II */
-fun subsetSumII(nums: IntArray, target: Int): List<List<Int>?> {
-    val state: MutableList<Int> = ArrayList() // 狀態（子集）
-    Arrays.sort(nums) // 對 nums 進行排序
+fun subsetSumII(nums: IntArray, target: Int): MutableList<MutableList<Int>?> {
+    val state = mutableListOf<Int>() // 狀態（子集）
+    nums.sort() // 對 nums 進行排序
     val start = 0 // 走訪起始點
-    val res: MutableList<List<Int>?> = ArrayList() // 結果串列（子集串列）
+    val res = mutableListOf<MutableList<Int>?>() // 結果串列（子集串列）
     backtrack(state, target, nums, start, res)
     return res
 }
@@ -57,7 +55,6 @@ fun subsetSumII(nums: IntArray, target: Int): List<List<Int>?> {
 fun main() {
     val nums = intArrayOf(4, 4, 5)
     val target = 9
-
     val res = subsetSumII(nums, target)
 
     println("輸入陣列 nums = ${nums.contentToString()}, target = $target")