LeetCode 15 3Sum [sort] <c++> 给出一个一维数组,找出其中所有和为零的三元组(元素集相同的视作同一个三元组)的集合. C++ 先自己写了一发,虽然过了,但跑了308 ms... 我的做法是先排序,扫一遍,处理出unorder_map<0-a[i],i>的hash表.再\(O(n^2)\)枚举前两个元素,查表直接知道第三个元素的位置,然后将三元组加入到答案集合中,通过枚举时添加的限制条件规避重复元素. 复杂度\(O(n^2)\),由于使用了hash表,常数…

传送门 15. 3Sum My Submissions Question Total Accepted: 108534 Total Submissions: 584814 Difficulty: Medium 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 su…

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 solut…

一.题目链接:https://leetcode.com/problems/3sum/ 二.题目大意: 3和问题是一个比较经典的问题,它可以看做是由2和问题(见http://www.cnblogs.com/wangkundentisy/p/7525356.html)演化而来的.题目的具体要求如下: 给定一个数组A,要求从A中找出这么三个元素a,b,c使得a + b + c = 0,返回由这样的a.b.c构成的三元组,且要保证三元组是唯一的.(即任意的两个三元组,它们里面的元素不能完全相同) 三.题…

题目链接 https://leetcode.com/problems/3sum/?tab=Description   Problem: 给定整数集合,找到所有满足a+b+c=0的元素组合,要求该组合不重复.   首先对给出的数组进行排序 Arrays.sort() 从第0个元素开始进行判断,对应的有最大值num[high] 1.当num[low]+num[high]== -num[i]时,此时可以将num[low],num[high],num[i]添加至list中     a. 当low<hig…

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: The solution set must not contain duplicate triplets. For example, given array S = [-1,…

n数求和,固定n-2个数,最后两个数在连续区间内一左一右根据当前求和与目标值比较移动,如果sum<target,移动较小数,否则,移动较大数 重复数处理: 使i为左至右第一个不重复数:while(i != 0 && i<n-2 && a[i] == a[i-1]) i++; 使r为右至左第一个不重复数(原序最后一个):while(r>i && r+1<n && a[r] == a[r+1]) r--; 15. 3Sum…

3Sum  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…

3sum: 1 class Solution { public: vector<vector<int>> threeSum(vector<int>& nums) { vector<vector<int>>result; vector<vector<int>>::iterator iter; vector<int>Middle; ; sort(nums.begin(),nums.end()); ;i<…

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: The solution set must not contain duplicate triplets. For example, given array S = [-1,…