invert_tree.cpp

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