// 226. Invert Binary Tree // given 'root' of binary tree, invert the tree and return its root #include struct TreeNode { int val; struct TreeNode *left; struct TreeNode *right; }; struct TreeNode *invertTree(struct TreeNode *root) { struct TreeNode *tmp; if (root == NULL) return NULL; tmp = root->left; root->left = root->right; root->right = tmp; invertTree(root->left); invertTree(root->right); return root; }