<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>>ans;
        vector<vector<int>>a;
        unordered_map<long double,int>mp;
        for(int i=0;i<nums.size();i++){
            mp.insert(make_pair(nums[i],i));
        }
        for(int i=0;i<nums.size();i++){
            for(int j=i+1;j<nums.size();j++){
                for(int k=j+1;k<nums.size();k++){
                    if(mp.find((double)target-nums[i]-nums[j]-nums[k])!=mp.end()&&i!=j&&i!=k&&i!=mp[target-nums[i]-nums[j]-nums[k]]&&j!=k&&j!=mp[target-nums[i]-nums[j]-nums[k]]&&k!=mp[target-nums[i]-nums[j]-nums[k]]){
                        vector<int>temp={nums[i],nums[j],nums[k],(int)target-nums[i]-nums[j]-nums[k]};
                        sort(temp.begin(),temp.end());
                        ans.insert(temp);
                    }
                }
            }
        }
        for(auto i:ans){
            a.push_back(i);
        }
        return a;
    }
};
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