[226] Invert Binary Tree

賺題數again...

偷看解答以後是個開心的打完收工 XD

/**

* Definition for a binary tree node.

* struct TreeNode {

* int val;

* struct TreeNode *left;

* struct TreeNode *right;

* };

*/

struct TreeNode* invertTree(struct TreeNode* root){

if (root == NULL)

return root;

struct TreeNode* tmp;

tmp = root->left;

root->left = root->right;

root->right = tmp;

invertTree(root->left);

invertTree(root->right);

return root;

}