leetcode[226]:Invert Binary Tree

Invert Binary Tree

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 fuck off.

struct TreeNode* invertTree(struct TreeNode* root) {   struct TreeNode *tmp1;   if(!root) return root;   if(!root->left && !root->right) return root;   if( root->left && !root->right)    {        root->right=invertTree(root->left);;        root->left = NULL;   }   else if( !root->left && root->right)    {        root->left=invertTree(root->right);        root->right = NULL;   }   else if( root->left && root->right)    {        tmp1 = root->left;        root->left = invertTree(root->right);        root->right = invertTree(tmp1);   }   return root;}

递归交换左右子树，注意空的情况。