15. 3sum

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        vector<vector<int>> pi;
        set<vector<int>> st;
        for(int i=0;i<nums.size();i++)
        {
            unordered_map<int,int> mp;
            for(int j=i+1;j<nums.size();j++)
            { vector<int> triplet;
                int target=-(nums[i]+nums[j]);
                if(mp.find(target)!=mp.end())
                { 
                    triplet.push_back(nums[i]);
                     triplet.push_back(nums[j]);
                      triplet.push_back(target);
                    sort(triplet.begin(), triplet.end()); 
                    st.insert(triplet); 
                }
              mp[nums[j]]=j;
           }
      
        }
       for(auto it: st)
       {
         pi.push_back(it);
       }
        return pi;
    }
};