From ef44b3f3be86dcb2207d861dfb13d3904a35affb Mon Sep 17 00:00:00 2001
From: frank-tian <zztian1024@sina.com>
Date: Mon, 19 Jul 2021 23:32:21 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=20Swift=20=E4=BB=A3=E7=A0=81?=
 =?UTF-8?q?=E5=AE=9E=E7=8E=B0?=
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---
 .../二叉树/二叉树的前序遍历(Morris).md        | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/animation-simulation/二叉树/二叉树的前序遍历(Morris).md b/animation-simulation/二叉树/二叉树的前序遍历(Morris).md
index a6722b8..95a141f 100644
--- a/animation-simulation/二叉树/二叉树的前序遍历(Morris).md
+++ b/animation-simulation/二叉树/二叉树的前序遍历(Morris).md
@@ -103,4 +103,41 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func preorderTraversal(_ root: TreeNode?) -> [Int] {
+        var list:[Int] = []
+        guard root != nil else {
+            return list
+        }
+        var p1 = root, p2: TreeNode?
+        while p1 != nil {
+            p2 = p1!.left
+            if p2 != nil {
+                //找到左子树的最右叶子节点
+                while p2!.right != nil && p2!.right !== p1 {
+                    p2 = p2!.right
+                }
+                //添加 right 指针，对应 right 指针为 null 的情况
+                if p2!.right == nil {
+                    list.append(p1!.val)
+                    p2!.right = p1
+                    p1 = p1!.left
+                    continue
+                }
+                //对应 right 指针存在的情况，则去掉 right 指针
+                p2!.right = nil
+            } else {
+                list.append(p1!.val)
+            }
+            //移动 p1
+            p1 = p1!.right
+        }
+        return list
+    }
+}
+```
+
 好啦，今天就看到这里吧，咱们下期见！
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