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/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)")
+        }
+    }
+}