feat: add swift implementation to lcof problem: No.34 (doocs#2904)

Author: klever34

lcof/面试题34. 二叉树中和为某一值的路径/README.md

@@ -381,6 +381,50 @@ public class Solution {
 }
 ```
 
+#### 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() { self.val = 0; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+ *         self.val = val
+ *         self.left = left
+ *         self.right = right
+ *     }
+ * }
+ */
+ 
+class Solution {
+    private var t = [Int]()
+    private var ans = [[Int]]()
+
+    func pathSum(_ root: TreeNode?, _ target: Int) -> [[Int]] {
+        dfs(root, target)
+        return ans
+    }
+
+    private func dfs(_ root: TreeNode?, _ s: Int) {
+        guard let root = root else {
+            return
+        }
+        t.append(root.val)
+        let remainingSum = s - root.val
+        if root.left == nil && root.right == nil && remainingSum == 0 {
+            ans.append(Array(t))
+        }
+        dfs(root.left, remainingSum)
+        dfs(root.right, remainingSum)
+        t.removeLast()
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题34. 二叉树中和为某一值的路径/Solution.swift

@@ -0,0 +1,39 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init() { self.val = 0; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+ *         self.val = val
+ *         self.left = left
+ *         self.right = right
+ *     }
+ * }
+ */
+ 
+class Solution {
+    private var t = [Int]()
+    private var ans = [[Int]]()
+
+    func pathSum(_ root: TreeNode?, _ target: Int) -> [[Int]] {
+        dfs(root, target)
+        return ans
+    }
+
+    private func dfs(_ root: TreeNode?, _ s: Int) {
+        guard let root = root else {
+            return
+        }
+        t.append(root.val)
+        let remainingSum = s - root.val
+        if root.left == nil && root.right == nil && remainingSum == 0 {
+            ans.append(Array(t))
+        }
+        dfs(root.left, remainingSum)
+        dfs(root.right, remainingSum)
+        t.removeLast()
+    }
+}