226. Invert Binary Tree

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226. Invert Binary Tree

Description

Difficulty: Easy

Related Topics: Tree, Depth-First Search, Breadth-First Search, Binary Tree

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

Example 1:

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

Example 2:

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

Example 3:

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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

Hints/Notes

Solution

Language: C++

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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 == nullptr) {
            return root;
        }
        TreeNode* left = invertTree(root->left);
        TreeNode* right = invertTree(root->right);

        root->left = right;
        root->right = left;

        return root;
    }
};