class Solution {
public:
    vector<vector<int> > fourSum(vector<int> &num, int target) {

        set< vector<int> >s;

        int n = num.size();

        vector<int> temp;
        vector< vector<int> > ans;

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

        for(int i = 0 ; i < (n - 3) ; i++ ) {

            for( int j = i+1 ; j < n-2 ; j++ ) {

                int k = j + 1, l = n - 1;

                while ( k < l ) {

                    int sum = num[i] + num[j] + num[k] + num[l];

                    if( sum == target ) {
                        temp.clear();
                        temp.push_back(num[i]);
                        temp.push_back(num[j]);
                        temp.push_back(num[k]);
                        temp.push_back(num[l]);
                        s.insert(temp);

                        k++;
                        l--;

                        while( k < l && num[l] == num[l+1]) {
                            l--;
                        }

                        while(k < l && num[k] == num[k-1] ) {
                            k++;
                        }


                    }
                    else if( sum < target ) {
                        k++;
                    }
                    else {
                        l--;
                    }
                }
            }
        }

        /*for( int i = ans.size() - 1 ; i >= 0 ; i-- ) {

            for( int j = i - 1 ; j >= 0 ; j-- ) {

                if( ans[i][0] == ans[j][0] && ans[i][1] == ans[j][1] && ans[i][2] == ans[j][2] ) {
                    ans.erase(ans.begin() + j);
                }
            }
        }*/


        for( set< vector<int> >::iterator itr = s.begin() ; itr != s.end() ; itr++ ) {
            ans.push_back(*itr);
        }

        return ans;

    }
};