class Solution {
public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        int n = nums.size();
        sort(nums.begin(), nums.end());
        set<vector<int>> set;
        vector<vector<int>> output;
        for(int i=0; i<n-3; i++){
            for(int j=i+1; j<n-2; j++){
                for(int k=j+1; k<n-1; k++){
                    for(int l=k+1; l<n; l++){
                        if((long long)nums[i] + (long long)nums[j] + (long long)nums[k] + 
                        (long long)nums[l] == target){
                            set.insert({nums[i], nums[j], nums[k], nums[l]});
                        }
                    }
                }
            }
        }
        for(auto it : set){
            output.push_back(it);
        }
        return output;
    }
};

// TC : O(n^4)
// SC : O(n)