Merge pull request #1829 from ZerenZhang2022/patch-3

Update 0226.翻转二叉树.md

problems/0226.翻转二叉树.md

@@ -359,7 +359,22 @@ class Solution:
                     queue.append(node.right)
         return root
 ```
-
+迭代法：广度优先遍历（层序遍历），和之前的层序遍历写法一致：
+```python
+class Solution:
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+        if not root: return root
+        from collections import deque
+        que=deque([root])    
+        while que:
+            size=len(que)
+            for i in range(size):
+                cur=que.popleft()
+                cur.left, cur.right = cur.right, cur.left
+                if cur.left: que.append(cur.left)
+                if cur.right: que.append(cur.right)
+        return root   
+```
 ### Go
 
 递归版本的前序遍历