力扣 226. 翻转二叉树

给你一棵二叉树的根节点 root ，翻转这棵二叉树，并返回其根节点。

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
struct TreeNode* invertTree(struct TreeNode* root) {
    if(!root){return NULL;}
    //struct TreeNode* tmp=(struct TreeNode*)malloc(sizeof(struct TreeNode*));
    //一个tmp指针不需要malloc，可直接定义
    struct TreeNode* tmp=root->left;
    root->left=root->right;
    root->right=tmp;
 
    invertTree(root->left);
    invertTree(root->right);
    return root;
    
}