# Invert Binary Tree Problem

## Description

LeetCode Problem 226.

Given the root of a binary tree, invert the tree, and return its root.

Example 1:

``````1
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Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
``````

Example 2:

``````1
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Input: root = [2,1,3]
Output: [2,3,1]
``````

Example 3:

``````1
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Input: root = []
Output: []
``````

Constraints:

• The number of nodes in the tree is in the range [0, 100].
• -100 <= Node.val <= 100

## Sample C++ Code

``````1
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/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode() : val(0), left(nullptr), right(nullptr) {}
*     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
*     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
if (root == NULL)
return root;
TreeNode* new_left = invertTree(root->right);
TreeNode* new_right = invertTree(root->left);
root->left = new_left;
root->right = new_right;
return root;
}
};
``````