<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>> answer;

        if (nums.size() < 4) {
            return answer;
        }

        vector<int> lastVec;
        sort(nums.begin(), nums.end());
        if(nums[0] == nums[nums.size()-1]) {
            if(nums[0] == 2) {
                vector<int> r1;
                r1.push_back(2);
                r1.push_back(2);
                r1.push_back(2);
                r1.push_back(2);
                answer.push_back(r1);
                return answer;
            }
        }
        
        for(int L1 = 0; L1 < nums.size()-3; L1++) {
            if (nums[L1] > target/4) {
                break;
            }

            for(int L2 = L1+1; L2 < nums.size()-2; L2++) {    
                for(int L3 = L2+1; L3 < nums.size()-1; L3++) {   
                    for(int L4 = L3+1; L4 < nums.size(); L4++) {

                        long total = nums[L1]+nums[L2];
                        total += nums[L3]+nums[L4];
                        if(total == target) {
                            vector<int> r1 = {nums[L1], nums[L2], nums[L3], nums[L4]};

                            if(lastVec.size() == 0) {
                                answer.push_back(r1);
                                lastVec = r1; 
                            } else if(lastVec != r1) {
                                if (lastVec[0] > r1[0]) {
                                    continue;
                                } else if (lastVec[0] == r1[0] && lastVec[1] > r1[1]) {
                                    continue;
                                } else if (lastVec[0] == r1[0] && lastVec[1] == r1[1] && lastVec[2] > r1[2]) {
                                    continue;
                                } else if (lastVec[0] == r1[0] && lastVec[1] == r1[1] && lastVec[2] == r1[2] && lastVec[3] > r1[3]) {
                                    continue;                                    
                                }            

                                answer.push_back(r1);
                                lastVec = r1;                              
                            }
                        }
                    }                     
                }                
            }        
        }
        return answer;
    }
};
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