leetcode-树练习-symmetric-tree

练习过的题目

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {

    public boolean help(TreeNode left, TreeNode right){
        if(left == null && right == null)return true;
        if(left == null