LeetCode_226_Invert_Binary_Tree.cpp

/*
  226. Invert Binary Tree

  Invert a binary tree.
  Example:
  Input:

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

Output:
     4
   /   \
  7     2
 / \   / \
9   6 3   1

Trivia:
This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew),
but you can’t invert a binary tree on a whiteboard so f*** off.
*/

class Solution {
public:
  TreeNode* invertTree( TreeNode* root ) {
    if( !root ) return root;
    TreeNode* node = root->left;
    root->left = invertTree( root->right );;
    root->right = invertTree( node );
    return root;
  }
};