题目
请完成一个函数,输入一个二叉树,该函数输出它的镜像。
例如输入:
4
/
2 7
/ \ /
1 3 6 9
镜像输出:
4
/
7 2
/ \ /
9 6 3 1
示例 1:
输入:root = [4,2,7,1,3,6,9]
输出:[4,7,2,9,6,3,1]
限制:
0 <= 节点个数 <= 1000
代码
Python
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def mirrorTree(self, root: TreeNode) -> TreeNode:
if not root: return # 终止条件,父结点为空
tmp = root.left # 暂存左儿子
root.left = self.mirrorTree(root.right) # 递归右儿子,更改左儿子
root.right = self.mirrorTree(tmp) # 递归左儿子,更改右儿子
return root
C++
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
TreeNode* mirrorTree(TreeNode* root) {
if (root==NULL) return NULL;
TreeNode *L=mirrorTree(root->right);
TreeNode *R=mirrorTree(root->left);
root->left=L;
root->right=R;
return root;
}
};