力扣第15题:三数之和

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        sort(nums.begin(),nums.end());
        vector<vector<int>> vv;
        for(int i=0;i<nums.size();i++)
        {
            if(nums[i]>0)
               break;
            if(i>0&&nums[i]==nums[i-1])
                continue;
             int left=i+1;
             int right=nums.size()-1;
             while(left<right)
             {
                 if(nums[i]+nums[left]+nums[right]>0)
                 {
                     right--;
                 }
                 else if(nums[i]+nums[left]+nums[right]<0)
                 {
                     left++;
                 }
                 else
                 {
                     vv.push_back({nums[i],nums[left],nums[right]});
                     while(left<right&&nums[left]==nums[left+1])
                          left++;
                     while(left<right&&nums[right-1]==nums[right])
                          right--;
                    left++;
                    right--;
                 }
             }
        }
        return vv;
    }
};