<p>Given an array <code>nums</code> of <code>n</code> integers, return <em>an array of all the <strong>unique</strong> quadruplets</em> <code>[nums[a], nums[b], nums[c], nums[d]]</code> such that:</p>

<ul>
	<li><code>0 &lt;= a, b, c, d&nbsp;&lt; n</code></li>
	<li><code>a</code>, <code>b</code>, <code>c</code>, and <code>d</code> are <strong>distinct</strong>.</li>
	<li><code>nums[a] + nums[b] + nums[c] + nums[d] == target</code></li>
</ul>

<p>You may return the answer in <strong>any order</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,0,-1,0,-2,2], target = 0
<strong>Output:</strong> [[-2,-1,1,2],[-2,0,0,2],[-1,0,0,1]]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,2,2,2,2], target = 8
<strong>Output:</strong> [[2,2,2,2]]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 200</code></li>
	<li><code>-10<sup>9</sup> &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
	<li><code>-10<sup>9</sup> &lt;= target &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution {
public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        set<vector<int>> result;
        vector<vector<int>> output;
        if(nums.size() < 4){
            return output;
        }
        sort(nums.begin(), nums.end());
        vector<int> top = nums;
        auto tr = unique(top.begin(), top.end());
        top.erase(tr, top.end());
        if(top.size() == 1 && (long long)top[0]*4 == target){
            output.push_back({top[0], top[0], top[0], top[0]});
            return output;
        }
        int n = nums.size();

        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){
                            result.insert({nums[i], nums[j], nums[k], nums[l]});
                        }
                    }
                }

            }
        }
     for(auto it: result){
        output.push_back(it);
     }
     return output;  
    }
};
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