LeetCode 3Sum
来源:互联网 发布:软件项目验收清单 编辑:程序博客网 时间:2024/05/19 15:21
Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.
Note:
- Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)
- The solution set must not contain duplicate triplets.
For example, given array S = {-1 0 1 2 -1 -4}, A solution set is: (-1, 0, 1) (-1, -1, 2)题意:找到三个数字和是0的结果集
思路:首先转换为求2个数字和的情况,枚举每一位,那么这位固定后,就能根据双指针法来处理这个问题啦
关键是去重的部分:1. 双指针法的头指针从枚举的下一位开始,这样就能排除前面枚举的结果
2. 对于每次枚举相邻两位是一样的话,我们就跳过
3. 对于双指针相邻两位一样的话,我们也跳过
class Solution {public: vector<vector<int> > threeSum(vector<int> &num) { vector<vector<int>> ans; sort(num.begin(), num.end()); for (int i = 0; i < num.size(); i++) { if (i && num[i] == num[i-1]) continue; int s = i + 1; int e = num.size() - 1; while (s < e) { if (s > i+1 && num[s] == num[s-1]) { s++; continue; } if (e < num.size() - 1 && num[e] == num[e+1]) { e--; continue; } int sum = num[i] + num[s] + num[e]; if (sum > 0) e--; else if (sum < 0) s++; else { vector<int> ve; ve.push_back(num[i]); ve.push_back(num[s]); ve.push_back(num[e]); ans.push_back(ve); s++; } } } return ans; }};
0 0
- 【Leetcode】3Sum (Sum)
- Leetcode:2Sum,3Sum
- 【Leetcode】3Sum Closest (Sum)
- leetcode 2 sum 3sum 4sum
- Leetcode 2SUM-3SUM-4SUM
- Leetcode-2sum,3sum,4sum
- leetcode 2 sum & 3 sum & 4 sum
- [LeetCode] 2Sum, 3Sum, 4Sum, 3SUm closet
- [LeetCode] K sum(2Sum、3Sum、4Sum)
- leetcode--sum集合:2sum,3sum,4sum
- leetcode --- 2 sum , 3 sum , 4 sum , k sum problem
- LeetCode: 3Sum
- LeetCode: 3 Sum Closest
- leetcode - 3 Sum
- leetcode - 3 sum closest
- leetcode 3Sum
- leetcode 3Sum Closest
- LeetCode: 3Sum
- 开发环境错误(很不注意就会出现的错误)
- HDOJ 1671 Phone List(字典树)
- 100个iOS开发/设计面试题汇总,你将如何作答?
- java概念
- 时间序列分析之 ARIMA 模型的JAVA实现
- LeetCode 3Sum
- STRUTS框架(web.xml,struts.xml,XXXvalidation.xml配置信息)个人心得
- android activity(通过一个按钮打开另一个acticity总结)
- Jsoncpp的使用
- 回调函数和接口回调的理解,有图更给力!
- 解决Ubuntu中update的问题(Reading package lists... Error!)
- MFC 视图类(CView)介绍
- 常用的Java代码汇总
- 移动支付的安全问题