Leetcode 226. Invert Binary Tree (Easy) (cpp)

/*

226. Invert Binary Tree (Easy)

Invert a binary tree.

4
/   \
2     7
/ \   / \
1   3 6   9
to
4
/   \
7     2
/ \   / \
9   6 3   1

*/
/**
* 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 || !(root -> left) && !(root -> right))
return root;
else {
swap(root -> left, root -> right);
invertTree(root -> left);
invertTree(root -> right);
}
return root;
}
};