From 0e75c5d92e619bffb60a63db4d606a492045b732 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9E=81=E5=AE=A2=E5=AD=A6=E4=BC=9F?= <qxuewei@yeah.net>
Date: Thu, 20 Jan 2022 20:32:17 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20257.=20=E4=BA=8C=E5=8F=89?=
 =?UTF-8?q?=E6=A0=91=E7=9A=84=E6=89=80=E6=9C=89=E8=B7=AF=E5=BE=84=20Swift?=
 =?UTF-8?q?=E7=89=88=E6=9C=AC?=
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---
 problems/0257.二叉树的所有路径.md | 65 +++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/problems/0257.二叉树的所有路径.md b/problems/0257.二叉树的所有路径.md
index cb837d87..7b5fc2e9 100644
--- a/problems/0257.二叉树的所有路径.md
+++ b/problems/0257.二叉树的所有路径.md
@@ -581,7 +581,72 @@ var binaryTreePaths = function(root) {
 };  
 ```
 
+Swift:
 
+> 递归/回溯
+```swift
+func binaryTreePaths(_ root: TreeNode?) -> [String] {
+    var res = [String]()
+    guard let root = root else {
+        return res
+    }
+    var path = [Int]()
+    _binaryTreePaths(root, path: &path, res: &res)
+    return res
+}
+func _binaryTreePaths(_ root: TreeNode, path: inout [Int], res: inout [String]) {
+    path.append(root.val)
+    if root.left ==  nil && root.right == nil {
+        var str = ""
+        for i in 0 ..< path.count - 1 {
+            str.append("\(path[i])->")
+        }
+        str.append("\(path.last!)")
+        res.append(str)
+        return
+    }
+    if let left = root.left {
+        _binaryTreePaths(left, path: &path, res: &res)
+        path.removeLast()
+    }
+    if let right = root.right {
+        _binaryTreePaths(right, path: &path, res: &res)
+        path.removeLast()
+    }
+}
+```
+
+> 迭代
+```swift
+func binaryTreePaths(_ root: TreeNode?) -> [String] {
+    var res = [String]()
+    guard let root = root else {
+        return res
+    }
+    var stackNode = [TreeNode]()
+    stackNode.append(root)
+    
+    var stackStr = [String]()
+    stackStr.append("\(root.val)")
+    
+    while !stackNode.isEmpty {
+        let node = stackNode.popLast()!
+        let str = stackStr.popLast()!
+        if node.left == nil && node.right == nil {
+            res.append(str)
+        }
+        if let left = node.left {
+            stackNode.append(left)
+            stackStr.append("\(str)->\(left.val)")
+        }
+        if let right = node.right {
+            stackNode.append(right)
+            stackStr.append("\(str)->\(right.val)")
+        }
+    }
+    return res
+}
+```
 
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>