Leetcode Week11

/*

在数组中找所有3个数相加等于0的子数组

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.

*/

class Solution {public:    vector<vector<int> >* v;      vector<vector<int>> threeSum(vector<int>& num) {        v = new vector<vector<int> >();        if(num.size()<3)        {            return *v;        }                sort(num.begin(),num.end());                for(int i=0;i<num.size()-2;i++)        {            if(i>0 && num[i]==num[i-1])                continue;                        for(int j=i+1;j<num.size();j++)            {                if(j>i+1 && num[j]==num[j-1])                    continue;                                int left = j+1;                int right = num.size()-1;                while(left<=right)                {                    int mid = left+(right-left)/2;                    if(num[i]+num[j]+num[mid] == 0)                    {                        vector<int> tmp;                        tmp.push_back(num[i]);                        tmp.push_back(num[j]);                        tmp.push_back(num[mid]);                                                v->push_back(tmp);                        break;                    }                    else if(num[i]+num[j]+num[mid]>0)                    {                        right = mid-1;                    }                    else                    {                        left = mid+1;                    }                }                            }        }                return *v;    }  };