LeetCode 0226 - Invert Binary Tree

Invert Binary Tree

Desicription

Invert a binary tree.

Example:

Input:

代码语言：javascript复制

     4
   /   
  2     7
 /    / 
1   3 6   9

Output:

代码语言：javascript复制

     4
   /   
  7     2
 /    / 
9   6 3   1

Trivia:

This problem was inspired by this original tweet by Max Howell:

Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so f*** off.

Solution

代码语言：javascript复制

/**
 * 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* invertTree(TreeNode* root) {
        if(root == nullptr) {
            return nullptr;
        }
        auto left_node = invertTree(root->left);
        auto right_node = invertTree(root->right);
        root->left = right_node;
        root->right = left_node;
        return root;
    }
};

binary google output this tree

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