<p>Given an integer array nums, return all the triplets <code>[nums[i], nums[j], nums[k]]</code> such that <code>i != j</code>, <code>i != k</code>, and <code>j != k</code>, and <code>nums[i] + nums[j] + nums[k] == 0</code>.</p>

<p>Notice that the solution set must not contain duplicate triplets.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [-1,0,1,2,-1,-4]
<strong>Output:</strong> [[-1,-1,2],[-1,0,1]]
<strong>Explanation:</strong> 
nums[0] + nums[1] + nums[2] = (-1) + 0 + 1 = 0.
nums[1] + nums[2] + nums[4] = 0 + 1 + (-1) = 0.
nums[0] + nums[3] + nums[4] = (-1) + 2 + (-1) = 0.
The distinct triplets are [-1,0,1] and [-1,-1,2].
Notice that the order of the output and the order of the triplets does not matter.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,1,1]
<strong>Output:</strong> []
<strong>Explanation:</strong> The only possible triplet does not sum up to 0.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> nums = [0,0,0]
<strong>Output:</strong> [[0,0,0]]
<strong>Explanation:</strong> The only possible triplet sums up to 0.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>3 &lt;= nums.length &lt;= 3000</code></li>
	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:
    vector<vector<int>> threeSum(vector<int>& nums) {
        set<vector<int>> v;
        vector<vector<int>> v1;
        vector<int> va, vb;
        set<int> sa, sb;
        sort(nums.begin(), nums.end());
        for(int i = 0; i < nums.size(); i++){
            if(nums[i] < 0) va.push_back(nums[i]);
            else vb.push_back(nums[i]);
        }
        sa.insert(va.begin(), va.end());
        sb.insert(vb.begin(), vb.end());
        if(vb.size() == 0) return v1;
        
        if(va.size() == 0){
            if(vb[2] != 0) return v1;
            else{
                v.insert({0, 0, 0});
                for(auto i : v) v1.push_back(i);
                return v1;
            }
        }
        else if(vb.size() > 2){
            if(vb[2] == 0){
                v.insert({0,0,0});
                //for(auto i : v) v1.push_back(i);
            }
        }
        for(int i = 0; i < va.size()-1; i++){
            for(int j = i+1; j < va.size(); j++){
                int a = va[i] + va[j];
                a *= -1;
                auto it = sb.find(a);
                if(it != sb.end()){
                    vector<int> vv;
                    vv.push_back(va[i]);
                    vv.push_back(va[j]);
                    vv.push_back(a);
                    v.insert(vv);
                }
            }
        }

        for(int i = 0; i < vb.size()-1; i++){
            for(int j = i+1; j < vb.size(); j++){
                int a = vb[i] + vb[j];
                a *= -1;
                auto it = sa.find(a);
                if(it != sa.end()){
                    vector<int> vv;
                    vv.push_back(vb[i]);
                    vv.push_back(vb[j]);
                    vv.push_back(a);
                    v.insert(vv);
                }
            }
        }
        for(auto i : v){
            v1.push_back(i);
        }
        return v1;
    }
};
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