<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>> redGraph(n), blueGraph(n);

        for(auto edge : redEdges){
            redGraph[edge[0]].push_back(edge[1]);
        }
        for(auto edge : blueEdges){
            blueGraph[edge[0]].push_back(edge[1]);
        }

        vector<int>result(n,-1);

        queue<tuple<int, int ,int>>q;
        q.push({0,0,0});// start from node 0 with red color(0) and dist 0;
        q.push({0,1,0});// start from node 0 with blue color(1) and dist 0

        vector<vector<bool>>visited(n, vector<bool>(2,false));

        while(!q.empty()){
            auto [node, color, dist] = q.front();
            q.pop();

            if(result[node] == -1){
                result[node] = dist;
            }

            auto nextGraph = (color == 0) ? blueGraph : redGraph;
            int nextColor = !color;

            for(int neighbour : nextGraph[node]){
                if(!visited[neighbour][nextColor]){
                    visited[neighbour][nextColor] = true;
                    q.push({neighbour, nextColor, dist+1});
                }
            }
        }

        return result;
    }
};
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