<p>We want to split a group of <code>n</code> people (labeled from <code>1</code> to <code>n</code>) into two groups of <strong>any size</strong>. Each person may dislike some other people, and they should not go into the same group.</p>

<p>Given the integer <code>n</code> and the array <code>dislikes</code> where <code>dislikes[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that the person labeled <code>a<sub>i</sub></code> does not like the person labeled <code>b<sub>i</sub></code>, return <code>true</code> <em>if it is possible to split everyone into two groups in this way</em>.</p>

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

<pre>
<strong>Input:</strong> n = 4, dislikes = [[1,2],[1,3],[2,4]]
<strong>Output:</strong> true
<strong>Explanation:</strong> The first group has [1,4], and the second group has [2,3].
</pre>

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

<pre>
<strong>Input:</strong> n = 3, dislikes = [[1,2],[1,3],[2,3]]
<strong>Output:</strong> false
<strong>Explanation:</strong> We need at least 3 groups to divide them. We cannot put them in two groups.
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 2000</code></li>
	<li><code>0 &lt;= dislikes.length &lt;= 10<sup>4</sup></code></li>
	<li><code>dislikes[i].length == 2</code></li>
	<li><code>1 &lt;= a<sub>i</sub> &lt; b<sub>i</sub> &lt;= n</code></li>
	<li>All the pairs of <code>dislikes</code> are <strong>unique</strong>.</li>
</ul>

class Solution {
public:
    
    
    int find(int u, int parent[]) {
        
        if(u==parent[u]){
            return u;
        }
       u = find(parent[u], parent);
        parent[u] = u;
        
        return u;
        
    }
    
    void unionn(int u, int v, int parent[]) {
        
      int  pu = find(u, parent);
      int  pv = find(v, parent);
        
        parent[pu] = pv;
        
        
    }
    
    
    bool possibleBipartition(int n, vector<vector<int>>& dislikes) {
        
        if(dislikes.size()==0){
            return true;
        }
        
        int a, b, first;
        
        int parent[n+1];
        
        for(int i=1; i<=n; i++) {
            
            parent[i] = i;
            
        }
      
        vector<int>adj[n+1];
        
        for(int i=0; i<dislikes.size(); i++) {
            
            a = dislikes[i][0];
            b = dislikes[i][1];
            
           adj[a].push_back(b);
           adj[b].push_back(a);
            
            
        }
        
        
        
        for(int i=1; i<=n; i++) {
            
            if(adj[i].size() == 0)continue;
            first = adj[i][0];
            if(find(i, parent)==find(first, parent)){
                    return false;
                }
                
            
            for(int j=0; j<adj[i].size(); j++) {
                
                if(find(i, parent)==find(adj[i][j], parent)) {
                    
                    return false;
                    
                }
                
                unionn(first, adj[i][j], parent);
                
            }
            
        }
        
        return true;
        
    }
};
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