feat: add swift implementation to lcof problem: No.68.1 (#2963)

Author: klever34

lcof/面试题68 - I. 二叉搜索树的最近公共祖先/README.md

@@ -416,6 +416,44 @@ function lowestCommonAncestor(
 }
 ```
 
+#### Swift
+
+```swift
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.left = nil
+ *         self.right = nil
+ *     }
+ * }
+ */
+
+class Solution {
+    func lowestCommonAncestor(_ root: TreeNode?, _ p: TreeNode?, _ q: TreeNode?) -> TreeNode? {
+        guard let p = p, let q = q else {
+            return nil
+        }
+
+        var node = root
+        while let current = node {
+            if current.val < p.val && current.val < q.val {
+                node = current.right
+            } else if current.val > p.val && current.val > q.val {
+                node = current.left
+            } else {
+                return current
+            }
+        }
+        return nil
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题68 - I. 二叉搜索树的最近公共祖先/Solution2.swift

@@ -0,0 +1,33 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.left = nil
+ *         self.right = nil
+ *     }
+ * }
+ */
+
+class Solution {
+    func lowestCommonAncestor(_ root: TreeNode?, _ p: TreeNode?, _ q: TreeNode?) -> TreeNode? {
+        guard let p = p, let q = q else {
+            return nil
+        }
+
+        var node = root
+        while let current = node {
+            if current.val < p.val && current.val < q.val {
+                node = current.right
+            } else if current.val > p.val && current.val > q.val {
+                node = current.left
+            } else {
+                return current
+            }
+        }
+        return nil
+    }
+}