<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) {
        unordered_map<int, int> numToInd;
        for (int i = 0; i < nums.size(); i++) {
            numToInd[nums[i]] = i;
        }

        vector<vector<int>> sum;
        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++) {
                    long long sum3 = ((long long)nums[i] + (long long)nums[j] + (long long)nums[k]) ; 
                    if(target<INT_MIN+sum3)break ; 
                    long long needed = (long long)target - ((long long)nums[i] + (long long)nums[j] + (long long)nums[k]);
                    if(needed>INT_MAX)break ; 
                    if (numToInd.find(needed) != numToInd.end()) {
                        int l = numToInd[needed];
                        if (l != k && l != j && l != i) {
                            vector<int> quad = {nums[i], nums[j], nums[k], nums[l]};
                            sort(quad.begin(), quad.end());
                            if (find(sum.begin(), sum.end(), quad) == sum.end()) {
                                sum.push_back(quad);
                            }
                        }
                    }
                }
            }
        }
        return sum;
    }
};
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