From 52ba6c2b35639233668d59eef75e41ceaf6d39bf 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, 14 Dec 2021 13:29:25 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20=E4=BA=8C=E5=8F=89?=
 =?UTF-8?q?=E6=A0=91=E7=9A=84=E9=80=92=E5=BD=92=E9=81=8D=E5=8E=86=20Swift?=
 =?UTF-8?q?=E7=89=88=E6=9C=AC?=
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---
 problems/二叉树的递归遍历.md | 51 ++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/problems/二叉树的递归遍历.md b/problems/二叉树的递归遍历.md
index 875e6169..0468b79b 100644
--- a/problems/二叉树的递归遍历.md
+++ b/problems/二叉树的递归遍历.md
@@ -409,5 +409,56 @@ int* postorderTraversal(struct TreeNode* root, int* returnSize){
 }
 ```
 
+Swift:
+前序遍历：（144.二叉树的前序遍历）
+```Swift
+func preorderTraversal(_ root: TreeNode?) -> [Int] {
+    var res = [Int]()
+    preorder(root, res: &res)
+    return res
+}
+func preorder(_ root: TreeNode?, res: inout [Int]) {
+    if root == nil {
+        return
+    }
+    res.append(root!.val)
+    preorder(root!.left, res: &res)
+    preorder(root!.right, res: &res)
+}
+```
+
+中序遍历：（94. 二叉树的中序遍历）
+```Swift
+func inorderTraversal(_ root: TreeNode?) -> [Int] {
+    var res = [Int]()
+    inorder(root, res: &res)
+    return res
+}
+func inorder(_ root: TreeNode?, res: inout [Int]) {
+    if root == nil {
+        return
+    }
+    inorder(root!.left, res: &res)
+    res.append(root!.val)
+    inorder(root!.right, res: &res)
+}
+```
+
+后序遍历：（145. 二叉树的后序遍历）
+```Swift
+func postorderTraversal(_ root: TreeNode?) -> [Int] {
+    var res = [Int]()
+    postorder(root, res: &res)
+    return res
+}
+func postorder(_ root: TreeNode?, res: inout [Int]) {
+    if root == nil {
+        return
+    }
+    postorder(root!.left, res: &res)
+    postorder(root!.right, res: &res)
+    res.append(root!.val)
+}
+```
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>