Invert Binary Tree.cpp

#include <iostream>

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