Topic describes

Complete a function that inputs a binary tree and outputs its mirror image.

For example, enter:

4 / \ 27 / \ / \ 1 3 6 9Copy the code

Mirror output:

4 / \ 7 2 / \ / 9 6 3 1Copy the code

Example 1:

Input: root = [4,2,7,1,3,6,9]Copy the code

Limitations:

  • 0 <= Number of nodes <= 1000

solution

Python3

# 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 root is None:
            return None
        root.left, root.right = root.right, root.left
        self.mirrorTree(root.left)
        self.mirrorTree(root.right)
        return root
Copy the code

Java

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public TreeNode mirrorTree(TreeNode root) { if (root == null) return null; TreeNode t = root.left; root.left = root.right; root.right = t; mirrorTree(root.left); mirrorTree(root.right); return root; }}Copy the code

JavaScript

/** * Definition for a binary tree node. * function TreeNode(val) { * this.val = val; * this.left = this.right = null; * } */ /** * @param {TreeNode} root * @return {TreeNode} */ var mirrorTree = function (root) { if (! root) return null; [root.left, root.right] = [root.right, root.left]; mirrorTree(root.left); mirrorTree(root.right); return root; };Copy the code

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 (TreeNode == root) {return nullptr; } mirrorTree(root->left); mirrorTree(root->right); std::swap(root->left, root->right); return root; }};Copy the code