[LeetCode]Same Tree

题目描述:(链接)

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.

解题思路:

迭代版

 1 /**
 2  * Definition for a binary tree node.
 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         stack<TreeNode *> cache;
14         cache.push(p);
15         cache.push(q);
16         
17         while (!cache.empty()) {
18             p = cache.top(); cache.pop();
19             q = cache.top(); cache.pop();
20             if (!p && !q) continue;
21             if (!p || !q) return false;
22             if (p->val != q->val) return false;
23             
24             cache.push(p->left);
25             cache.push(q->left);
26             cache.push(p->right);
27             cache.push(q->right);
28         }
29         
30         return true;
31     }
32 };

递归版：

 1 /**
 2  * Definition for a binary tree node.
 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         if (!p && !q) return true;
14         if (!p || !q) return false;
15         if (p->val != q->val) return false;
16         
17         return isSameTree(p->left, q->left) && isSameTree(p->right, q->right); 
18     }
19 };

 

posted @ 2015-12-01 19:36  skycore  阅读(139)  评论(0)  编辑  收藏  举报