<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<pair<int, int>>> adj(n);
        for(int i=0; i<redEdges.size(); i++){
            adj[redEdges[i][0]].push_back({redEdges[i][1], 0});
        }
        for(int i=0; i<blueEdges.size(); i++){
            adj[blueEdges[i][0]].push_back({blueEdges[i][1], 1});
        }

        vector<int> rr(n, INT_MAX);
        vector<int> bb(n, INT_MAX);
        rr[0] = 0;
        bb[0] = 0;

        queue<pair<int, int>> q;
        q.push({0, 1});
        q.push({0, 0});

        while(!q.empty()){

            int node = q.front().first;
            int clr = q.front().second;
            q.pop();

            for(auto i: adj[node]){
                int nxtnbr = i.first;
                int nxtclr = i.second;
                if(clr == 0 && nxtclr == 1 && bb[nxtnbr] > rr[node]+1){
                    bb[nxtnbr] = rr[node]+1;
                    q.push({nxtnbr, nxtclr});
                }
                if(clr == 1 && nxtclr == 0 && rr[nxtnbr] > bb[node]+1){
                    rr[nxtnbr] = bb[node]+1;
                    q.push({nxtnbr, nxtclr});
                }
            }
        }

        vector<int> ans(n);
        for(int i=0; i<n; i++){
            ans[i] = min(rr[i], bb[i]);
            if(ans[i] == INT_MAX){
                ans[i] = -1;
            }
        }
        
        return ans;
    }
};
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