<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 {
    int arranged[3000] = {0};

public:
    bool possibleBipartition(int n, vector<vector<int>>& dislikes) {
        bool nothingHappend = false;
        bool ableToArrangeNew = true;
        bool nothingHappendLast = false;
        if (dislikes.size() == 0)
            return true;
        for (int i = 0; i < 3 * n; i++) {
            nothingHappendLast = nothingHappend;
            nothingHappend = true;
            for (int i = 0; i < dislikes.size(); i++) {
                int a = dislikes[i][0];
                int b = dislikes[i][1];
                if (arranged[dislikes[i][0]] != 0 &&
                    arranged[dislikes[i][1]] != 0) {
                    if (arranged[a] == arranged[b])
                        return false;
                    continue;
                }

                if (arranged[dislikes[i][0]] != 0 &&
                    arranged[dislikes[i][1]] == 0) {

                    arranged[b] = ((arranged[a] == 1) ? 2 : 1);
                }
                if (arranged[dislikes[i][0]] == 0 &&
                    arranged[dislikes[i][1]] != 0) {

                    arranged[a] = ((arranged[b] == 1) ? 2 : 1);
                }
                if (arranged[dislikes[i][0]] == 0 &&
                    arranged[dislikes[i][1]] == 0) {
                    if (!ableToArrangeNew)
                        continue;
                    ableToArrangeNew = false;
                    arranged[a] = 1;
                    arranged[b] = 2;
                }
                nothingHappend = false;
                for (int j = 0; j < dislikes.size(); j++) {
                    if (dislikes[j][0] == a) {
                        if (arranged[dislikes[j][1]] == arranged[a])
                            return false;
                        else
                            arranged[dislikes[j][1]] = arranged[b];
                    }
                    if (dislikes[j][1] == a) {
                        if (arranged[dislikes[j][0]] == arranged[a])
                            return false;
                        else
                            arranged[dislikes[j][0]] = arranged[b];
                    }
                    if (dislikes[j][0] == b) {
                        if (arranged[dislikes[j][1]] == arranged[b])
                            return false;
                        else
                            arranged[dislikes[j][1]] = arranged[a];
                    }
                    if (dislikes[j][1] == b) {
                        if (arranged[dislikes[j][0]] == arranged[b])
                            return false;
                        else
                            arranged[dislikes[j][0]] = arranged[a];
                    }
                }
            }
            if (nothingHappend)
                ableToArrangeNew = true;
        }
        return true;
    }
};
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