leetcode题记:Same Tree

港控/mmm° 2022-05-18 05:57 97阅读 0赞

### 编程语言：JAVA ###

### 题目描述： ###

Given two binary trees, write a function to check if they are the same or not.
    
    Two binary trees are considered the same if they are structurally identical and the nodes have the same value.
    
    Example 1:
    
    Input:    
             1         1
              / \       / \
             2   3     2   3
    
            [1,2,3],   [1,2,3]
    
    Output: true
    Example 2:
    
    Input:    
     1         1
           /           \
             2             2
    
            [1,2],     [1,null,2]
    
    Output: false
    Example 3:
    
    Input:     
    1         1
              / \       / \
             2   1     1   2
    
            [1,2,1],   [1,1,2]
    
    Output: false

### 提交反馈： ###

57 / 57 test cases passed.
    Status: Accepted
    Runtime: 3 ms
    Submitted: 3 minutes ago
    You are here! 
    Your runtime beats 98.53 % of java submissions.

### 解题思路： ###

最开始的想法是遍历二叉树，然后存入StringBuffer中，比较两个字符串是否相同。
     百度参考大神博客之后，发现这样的办法虽然也可以完成，但是太笨了。
    直接用递归方法，结束条件为两颗树都为空或者其中一颗为空或者p.val不等于q.val;

### 代码： ###

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