标签：
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:
For example, given array S = {-1 0 1 2 -1 -4},
A solution set is:
(-1, 0, 1)
(-1, -1, 2)
class Solution { public: vector<vector<int> > threeSum(vector<int> &num) { vector<vector<int>> res; if(num.size()<3) return res; sort(num.begin(),num.end()); for(int i=0;i<num.size();i++) { if((i>0)&&(num[i]==num[i-1])) { continue; } int j=i+1; int k=num.size()-1; while(j<k) { if((j>i+1)&&(num[j]==num[j-1])) { j++; continue; } if((k<num.size()-1)&&(num[k]==num[k+1])) { k--; continue; } int sum=num[i]+num[j]+num[k]; if(sum<0)j++; else if(sum>0)k--; else { vector<int> temp; temp.push_back(num[i]); temp.push_back(num[j]); temp.push_back(num[k]); res.push_back(temp); j++; k--; } } } return res; } };
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原文地址：http://www.cnblogs.com/Vae98Scilence/p/4283686.html
