<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>> finalAns;
        sort(nums.begin(), nums.end());
        int vecSize = nums.size();

        for (int i = 0; i < vecSize; i++) {
            for (int j = i + 1; j < vecSize; j++) {
                int s = j + 1, e = vecSize - 1;

                while (s < e) {
                    long long int sum = nums[i];
                    sum += nums[j];
                    sum += nums[s];
                    sum += nums[e];
                    if (sum == target) {
                        vector<int> answer;
                        answer.push_back(nums[i]);
                        answer.push_back(nums[j]);
                        answer.push_back(nums[s]);
                        answer.push_back(nums[e]);
                        finalAns.push_back(answer);
                        e--;
                    } else if (sum < target) {
                        s++;
                    } else {
                        e--;
                    }
                }
            }
        }
        set<vector<int>> s;

        for (int i = 0; i < finalAns.size(); i++) {
            s.insert(finalAns[i]);
        }

        finalAns.clear();

        for (auto it = s.begin(); it != s.end(); it++) {
            finalAns.push_back(*it);
        }

        return finalAns;
    }
};
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