LeetCode -- Same Tree

题目描述：
Given two binary trees, write a function to check if they are equal or not.


Two binary trees are considered equal if they are structurally identical and the nodes have the same value.


比较两个二叉树是否完全相同。


思路：
直接对两个树从根节点同时DFS，使用全局成员来记录是否相等即可。




实现代码：

/** * Definition for a binary tree node. * public class TreeNode { *     public int val; *     public TreeNode left; *     public TreeNode right; *     public TreeNode(int x) { val = x; } * } */public class Solution {    public bool IsSameTree(TreeNode p, TreeNode q)     {        CompareTree(p, q);    return _same;    }private bool _same = true;private void CompareTree(TreeNode p , TreeNode q){if(!_same){return;}if(p == null && q == null){return ;}if(p == null && q != null || q == null && p != null || p.val != q.val){_same = false;return;}CompareTree(p.left, q.left);CompareTree(p.right, q.right);}}