<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:
    bool dfs(int src, auto &v, auto &c, auto &vi, int val) {
        if(vi[src]) {
            return true;
        }
        vi[src] = true;
        c[src] = val;
        int nextVal = val == 0? 1:0;
        bool ans = true;
        for(auto des:v[src]) {
            if (vi[des] && c[des] == val) {
                ans = ans && false;
            } else {
                ans = ans && dfs(des, v, c, vi, nextVal);
            }
        }
        return ans;
    }
    bool possibleBipartition(int n, vector<vector<int>>& dislikes) {
        vector<int>c(n+1, -1);
        vector<bool>vi(n+1, false);
        int num = dislikes.size();
        vector<vector<int>>v(n+1, vector<int>(0));
        for(int i=0; i<num; i++) {
            int src = dislikes[i][0];
            int des = dislikes[i][1];
            v[src].push_back(des);
            v[des].push_back(src);
        }
        bool ans = true;
        for(int i=1; i<=n; i++) {
            if (!vi[i]) {
                ans = ans && dfs(i, v, c, vi, 0);
            }
        }
        
        return ans;

    }
};
68778