Wins the Offer (XVIII): binary tree mirror

Wins the Offer (XVIII): binary tree mirror

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First, the primer

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Second, the title

Operation of a given binary tree, the binary tree is converted into a source image.

The binary image is defined:

1, ideas

After the first exchange of two child nodes of the root node, we noticed that the child node is node 10,6 remain the same, so we also need to exchange about child node of the two nodes. After doing these two exchanges, we have done through all the non-leaf node. At this point after the conversion tree is just a mirror of the original tree. Switching mode is shown below:

So we can do first two child nodes sequentially switched below the root node, the exchange done about recursive call node will eventually transform the entire binary tree Mirrors -

2, programming

python2.7

Code implementation:

# -*- 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
        else:
            root.left,root.right = root.right,root.left
            self.Mirror(root.left)
            self.Mirror(root.right)
            return root

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