<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) {
        vector<vector<int>> res;
        sort(nums.begin(),nums.end());
        int n=nums.size();
        if(n<4) return {};
        if(nums[0]==nums[n-1]){
            if((long long)nums[0]+nums[0]+nums[0]+nums[0]==target){
                return {{nums[0],nums[0],nums[0],nums[0]}};
            }
        }
        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(nums[i]==nums[j]&& nums[j]==nums[k] && nums[k]==nums[l] && target<nums[i]) continue;
                        long long sum=(long long)nums[i]+nums[j]+nums[k]+nums[l];
                        if(sum==target){
                            vector<int> temp={nums[i],nums[j],nums[k],nums[l]};
                            sort(temp.begin(),temp.end());
                            if(find(res.begin(),res.end(),temp)==res.end()){
                                res.push_back(temp);
                            }
                        }
                    }
                }
            }
        }
        if(res.empty()) return {};
        return res;
    }
};
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