4 Sum.cpp

#include<bits/stdc++.h>
using namespace std;

class Solution 
{

public:

    vector<vector<int>> fourSum(vector<int>& nums, int target)
    {

        int n = nums.size();

        

        sort(nums.begin(),nums.end());

      

       set<vector<int>> sv;

        for(int i=0;i<n;i++)

        {

            for(int j=i+1;j<n;j++)

            {

    

                for(int k=j+1;k<n;k++)

                { 

                  

                   int x = (long long)target - 

                           (long long)nums[i]-

                           (long long)nums[j]-(long long)nums[k];

                   

                        if(binary_search(nums.begin()+k+1,nums.end(),x))
                        {

                            vector<int> v;

                            v.push_back(nums[i]);

                            v.push_back(nums[j]);

                            v.push_back(nums[k]);

                            v.push_back(x);

                            sort(v.begin(),v.end());

                            sv.insert(v);

                        }

                }

            }

        }

        vector<vector<int>> res(sv.begin(),sv.end());

        return res;

    }

};

int main()

{

    Solution obj;

    vector<int> v{1,0,-1,0,-2,2};

    

    vector<vector<int>> sum=obj.fourSum(v,0);

    cout<<"The unique quadruplets are"<<endl;

    for (int i = 0; i < sum.size(); i++)
    {

        for (int j = 0; j < sum[i].size(); j++)

            cout << sum[i][j] << " ";

        cout << endl;

    }

}