From 3d0ce431d83ac814ab8479d9392c6a6e5e022366 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: Tue, 18 Jan 2022 13:18:36 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20110.=E5=B9=B3=E8=A1=A1?=
 =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=A0=91=20Swift=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0110.平衡二叉树.md | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/problems/0110.平衡二叉树.md b/problems/0110.平衡二叉树.md
index c0914f05..9d43407a 100644
--- a/problems/0110.平衡二叉树.md
+++ b/problems/0110.平衡二叉树.md
@@ -730,5 +730,33 @@ bool isBalanced(struct TreeNode* root){
 }
 ```
 
+## Swift:
+
+>递归
+```swift
+func isBalanced(_ root: TreeNode?) -> Bool {
+    // -1 已经不是平衡二叉树
+    return getHeight(root) == -1 ? false : true
+}
+func getHeight(_ root: TreeNode?) -> Int {
+    guard let root = root else {
+        return 0
+    }
+    let leftHeight = getHeight(root.left)
+    if leftHeight == -1 {
+        return -1
+    }
+    let rightHeight = getHeight(root.right)
+    if rightHeight == -1 {
+        return -1
+    }
+    if abs(leftHeight - rightHeight) > 1 {
+        return -1
+    } else {
+        return 1 + max(leftHeight, rightHeight)
+    }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

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 2/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20257.=20=E4=BA=8C?=
 =?UTF-8?q?=E5=8F=89=E6=A0=91=E7=9A=84=E6=89=80=E6=9C=89=E8=B7=AF=E5=BE=84?=
 =?UTF-8?q?=20Swift=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 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>