<p>You are given an integer <code>n</code>, the number of nodes in a directed graph where the nodes are labeled from <code>0</code> to <code>n - 1</code>. Each edge is red or blue in this graph, and there could be self-edges and parallel edges.</p>

<p>You are given two arrays <code>redEdges</code> and <code>blueEdges</code> where:</p>

<ul>
	<li><code>redEdges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is a directed red edge from node <code>a<sub>i</sub></code> to node <code>b<sub>i</sub></code> in the graph, and</li>
	<li><code>blueEdges[j] = [u<sub>j</sub>, v<sub>j</sub>]</code> indicates that there is a directed blue edge from node <code>u<sub>j</sub></code> to node <code>v<sub>j</sub></code> in the graph.</li>
</ul>

<p>Return an array <code>answer</code> of length <code>n</code>, where each <code>answer[x]</code> is the length of the shortest path from node <code>0</code> to node <code>x</code> such that the edge colors alternate along the path, or <code>-1</code> if such a path does not exist.</p>

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

<pre>
<strong>Input:</strong> n = 3, redEdges = [[0,1],[1,2]], blueEdges = []
<strong>Output:</strong> [0,1,-1]
</pre>

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

<pre>
<strong>Input:</strong> n = 3, redEdges = [[0,1]], blueEdges = [[2,1]]
<strong>Output:</strong> [0,1,-1]
</pre>

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

<ul>
	<li><code>1 &lt;= n &lt;= 100</code></li>
	<li><code>0 &lt;= redEdges.length,&nbsp;blueEdges.length &lt;= 400</code></li>
	<li><code>redEdges[i].length == blueEdges[j].length == 2</code></li>
	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub>, u<sub>j</sub>, v<sub>j</sub> &lt; n</code></li>
</ul>

class Solution {
public:
    vector<int> shortestAlternatingPaths(int n, vector<vector<int>>& redEdges, vector<vector<int>>& blueEdges) {
        vector<vector<int>> redAdj(n), blueAdj(n);
        vector<int> dis(n, -1);
        vector<vector<int>> redVis(n, vector<int>(n, 0)), blueVis(n, vector<int>(n, 0));

        for(int i = 0; i < redEdges.size(); i++)
        {
            redAdj[redEdges[i][0]].push_back(redEdges[i][1]);
        }

        for(int i = 0; i < blueEdges.size(); i++)
        {
            blueAdj[blueEdges[i][0]].push_back(blueEdges[i][1]);
        }

        queue<pair<int, pair<int, int>>> q;
        q.push({0, {0, -1}});
        dis[0] = 0;

        //red -> 0
        //blue -> 1

        while(!q.empty())
        {
            auto it = q.front();
            q.pop();
            int node = it.first;
            int d = it.second.first;
            int color = it.second.second;

            if(dis[node] == -1)
            {
                dis[node] = d;
            }

            if(color == -1)    //can be both
            {
                for(auto it: redAdj[node])
                {
                    if(redVis[node][it] == 0)
                    {
                        redVis[node][it]++;
                        q.push({it, {d + 1, 0}});
                    }
                }

                for(auto it: blueAdj[node])
                {
                    if(blueVis[node][it] == 0)
                    {
                        blueVis[node][it]++;
                        q.push({it, {d + 1, 1}});
                    }
                }
            }

            else if(color == 0) //only blue possible
            {
                for(auto it: blueAdj[node])
                {
                    if(blueVis[node][it] == 0)
                    {
                        blueVis[node][it]++;
                        q.push({it, {d + 1, 1}});
                    }
                }
            }

            else //only red possible
            {
                for(auto it: redAdj[node])
                {
                    if(redVis[node][it] == 0)
                    {
                        redVis[node][it]++;
                        q.push({it, {d + 1, 0}});
                    }
                }
            }
        }

        return dis;
    }
};
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