100. Same Tree 相同的树

@TOC

[LeetCode]

Total Accepted: 126017 Total Submissions: 291619 Difficulty: Easy

# 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
``````

# 解题方法

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if(p==null && q==null){
return true;
}
if(p==null || q==null){//注意是在p/q都不为空的情况下有一个为空，说明另外一个不为空
return false;
}
if(p.val!=q.val){//注意是不相等返回False，相等的话需要继续进行子节点的判断
return false;
}
return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
}
}
``````

AC:0ms

``````# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def isSameTree(self, p, q):
"""
:type p: TreeNode
:type q: TreeNode
:rtype: bool
"""
if not p and not q:
return True
if not p or not q:
return False
return p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)
``````

# 日期

2016/4/30 1:17:33 2018 年 10 月 8 日 —— 终于开学了。 2018 年 11 月 14 日 —— 很严重的雾霾