Feature/chapter searching swift (#673)

* fix: remove binary_search_edge

* feat: add Swift codes for binary_search_insertion article

* feat: add Swift codes for binary_search_edge article

codes/swift/Package.swift

@@ -48,6 +48,7 @@ let package = Package(
         .executable(name: "graph_dfs", targets: ["graph_dfs"]),
         // chapter_searching
         .executable(name: "binary_search", targets: ["binary_search"]),
+        .executable(name: "binary_search_insertion", targets: ["binary_search_insertion"]),
         .executable(name: "binary_search_edge", targets: ["binary_search_edge"]),
         .executable(name: "two_sum", targets: ["two_sum"]),
         .executable(name: "linear_search", targets: ["linear_search"]),
@@ -91,6 +92,7 @@ let package = Package(
         // helper
         .target(name: "utils", path: "utils"),
         .target(name: "graph_adjacency_list_target", dependencies: ["utils"], path: "chapter_graph", sources: ["graph_adjacency_list_target.swift"], swiftSettings: [.define("TARGET")]),
+        .target(name: "binary_search_insertion_target", path: "chapter_searching", sources: ["binary_search_insertion_target.swift"], swiftSettings: [.define("TARGET")]),
         // chapter_computational_complexity
         .executableTarget(name: "time_complexity", path: "chapter_computational_complexity", sources: ["time_complexity.swift"]),
         .executableTarget(name: "worst_best_time_complexity", path: "chapter_computational_complexity", sources: ["worst_best_time_complexity.swift"]),
@@ -134,7 +136,8 @@ let package = Package(
         .executableTarget(name: "graph_dfs", dependencies: ["utils", "graph_adjacency_list_target"], path: "chapter_graph", sources: ["graph_dfs.swift"]),
         // chapter_searching
         .executableTarget(name: "binary_search", path: "chapter_searching", sources: ["binary_search.swift"]),
-        .executableTarget(name: "binary_search_edge", path: "chapter_searching", sources: ["binary_search_edge.swift"]),
+        .executableTarget(name: "binary_search_insertion", path: "chapter_searching", sources: ["binary_search_insertion.swift"]),
+        .executableTarget(name: "binary_search_edge", dependencies: ["binary_search_insertion_target"], path: "chapter_searching", sources: ["binary_search_edge.swift"]),
         .executableTarget(name: "two_sum", path: "chapter_searching", sources: ["two_sum.swift"]),
         .executableTarget(name: "linear_search", dependencies: ["utils"], path: "chapter_searching", sources: ["linear_search.swift"]),
         .executableTarget(name: "hashing_search", dependencies: ["utils"], path: "chapter_searching", sources: ["hashing_search.swift"]),

codes/swift/chapter_searching/binary_search_edge.swift

@@ -0,0 +1,51 @@
+/**
+ * File: binary_search_edge.swift
+ * Created Time: 2023-08-06
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import binary_search_insertion_target
+
+/* 二分查找最左一个 target */
+func binarySearchLeftEdge(nums: [Int], target: Int) -> Int {
+    // 等价于查找 target 的插入点
+    let i = binarySearchInsertion(nums: nums, target: target)
+    // 未找到 target ，返回 -1
+    if i == nums.count || nums[i] != target {
+        return -1
+    }
+    // 找到 target ，返回索引 i
+    return i
+}
+
+/* 二分查找最右一个 target */
+func binarySearchRightEdge(nums: [Int], target: Int) -> Int {
+    // 转化为查找最左一个 target + 1
+    let i = binarySearchInsertion(nums: nums, target: target + 1)
+    // j 指向最右一个 target ，i 指向首个大于 target 的元素
+    let j = i - 1
+    // 未找到 target ，返回 -1
+    if j == -1 || nums[j] != target {
+        return -1
+    }
+    // 找到 target ，返回索引 j
+    return j
+}
+
+@main
+enum BinarySearchEdge {
+    /* Driver Code */
+    static func main() {
+        // 包含重复元素的数组
+        let nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15]
+        print("\n数组 nums = \(nums)")
+
+        // 二分查找左边界和右边界
+        for target in [6, 7] {
+            var index = binarySearchLeftEdge(nums: nums, target: target)
+            print("最左一个元素 \(target) 的索引为 \(index)")
+            index = binarySearchRightEdge(nums: nums, target: target)
+            print("最右一个元素 \(target) 的索引为 \(index)")
+        }
+    }
+}

codes/swift/chapter_searching/binary_search_insertion.swift

@@ -0,0 +1,67 @@
+/**
+ * File: binary_search_insertion.swift
+ * Created Time: 2023-08-06
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+/* 二分查找插入点（无重复元素） */
+func binarySearchInsertionSimple(nums: [Int], target: Int) -> Int {
+    var i = 0, j = nums.count - 1 // 初始化双闭区间 [0, n-1]
+    while i <= j {
+        let m = i + (j - i) / 2 // 计算中点索引 m
+        if nums[m] < target {
+            i = m + 1 // target 在区间 [m+1, j] 中
+        } else if nums[m] > target {
+            j = m - 1 // target 在区间 [i, m-1] 中
+        } else {
+            return m // 找到 target ，返回插入点 m
+        }
+    }
+    // 未找到 target ，返回插入点 i
+    return i
+}
+
+/* 二分查找插入点（存在重复元素） */
+public func binarySearchInsertion(nums: [Int], target: Int) -> Int {
+    var i = 0, j = nums.count - 1 // 初始化双闭区间 [0, n-1]
+    while i <= j {
+        let m = i + (j - i) / 2 // 计算中点索引 m
+        if nums[m] < target {
+            i = m + 1 // target 在区间 [m+1, j] 中
+        } else if nums[m] > target {
+            j = m - 1 // target 在区间 [i, m-1] 中
+        } else {
+            j = m - 1 // 首个小于 target 的元素在区间 [i, m-1] 中
+        }
+    }
+    // 返回插入点 i
+    return i
+}
+
+#if !TARGET
+
+@main
+enum BinarySearchInsertion {
+    /* Driver Code */
+    static func main() {
+        // 无重复元素的数组
+        var nums = [1, 3, 6, 8, 12, 15, 23, 26, 31, 35]
+        print("\n数组 nums = \(nums)")
+        // 二分查找插入点
+        for target in [6, 9] {
+            let index = binarySearchInsertionSimple(nums: nums, target: target)
+            print("元素 \(target) 的插入点的索引为 \(index)")
+        }
+
+        // 包含重复元素的数组
+        nums = [1, 3, 6, 6, 6, 6, 6, 10, 12, 15]
+        print("\n数组 nums = \(nums)")
+        // 二分查找插入点
+        for target in [2, 6, 20] {
+            let index = binarySearchInsertion(nums: nums, target: target)
+            print("元素 \(target) 的插入点的索引为 \(index)")
+        }
+    }
+}
+
+#endif

codes/swift/chapter_searching/binary_search_insertion_target.swift

@@ -0,0 +1 @@
+binary_search_insertion.swift