<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>> v;
        sort(nums.begin(), nums.end());
        if (nums[0] > 0 && target <= 0)
            return v;
        for(int i = 0; i < nums.size(); i++) {
            for(int j = i+1; j< nums.size(); j++) {
                for(int k = j+1, l = nums.size()-1; k < l; ) {
                        int64_t c = nums[i] + nums[j];
                        c += nums[k] + nums[l];
                        if (c == target) {
                            vector<int> vec;
                            vec.push_back(nums[i]);
                            vec.push_back(nums[j]);
                            vec.push_back(nums[k]);
                            vec.push_back(nums[l]);
                            v.push_back(vec);
                            k++;
                        } else if (c > target)
                            l--;
                    else
                        k++;
                }
            }
        }
        sort(v.begin(), v.end());
        vector<vector<int>>::iterator it=unique(v.begin(),v.begin()+v.size());
        v.resize(distance(v.begin(),it));
        return v;
    }
};
377266