3sum来自LeetCode

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