dsa-competitive-programming/leetcode/lc15/threesome.cpp

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