剑指offer 二叉树的镜像

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二叉树的镜像

题目

操作给定的二叉树，将其变换为源二叉树的镜像。
输入描述:

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二叉树的镜像定义：源二叉树
    	    8
    	   /  \
    	  6   10
    	 / \  / \
    	5  7 9 11
    	镜像二叉树
    	    8
    	   /  \
    	  10   6
    	 / \  / \
    	11 9 7  5

方法

方法1：递归

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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回镜像树的根节点
    def Mirror(self, root):
        # write code here
        if not root:
            return

        root.left,root.right=root.right,root.left
        self.Mirror(root.left)
        self.Mirror(root.right)
        return root

方法2：迭代

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# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回镜像树的根节点
    def Mirror(self, root):
        # write code here
        if not root:
            return
        stack=[root]
        while stack:
            node=stack.pop()     
            if not node:
                continue
            node.left,node.right=node.right,node.left
            stack.append(node.right)
            stack.append(node.left)

        return root
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# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回镜像树的根节点
    def Mirror(self, root):
        # write code here
        if not root:
            return

        stack=[root]
        while stack:
            node=stack.pop()
            if node:
                node.left,node.right=node.right,node.left
                stack.append(node.right)
                stack.append(node.left)

```                

```python
# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回镜像树的根节点
    def Mirror(self, root):
        # write code here
        if not root:
            return

        stack=[]
        node=root
        while node or stack:
            while node:
                node.left,node.right=node.right,node.left  # 此两句代码不能交换顺序
                stack.append(node.right)
                node=node.left
            node=stack.pop()
        return root