invert-binary-tree.cpp

#include <iostream>

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) return NULL;

        TreeNode* p = root->left;
        root->left = root->right;
        root->right = p;

        invertTree(root->left);
        invertTree(root->right);

        return root;
    }
};