Same Tree

2013.12.31 22:56

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.

Solution:

  Check the root, the left subtree and the right subtree, recursively. That's the answer.

  Time complexity is O(min(m, n)), where m and n are the numbers of nodes in both trees.

  Space complexity is O(1).

Accepted code:

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isSameTree(TreeNode *p, TreeNode *q) {
13         // Note: The Solution object is instantiated only once and is reused by each test case.
14         if(p == nullptr || q == nullptr){
15             return p == q;
16         }else{
17             if(p->val == q->val){
18                 return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
19             }else{
20                 return false;
21             }
22         }
23     }
24 };

 

 posted on 2013-12-31 23:14  zhuli19901106  阅读(208)  评论(0编辑  收藏  举报