<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<vector<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> ans(n,INT_MAX);
        vector<vector<vector<int>>> visited(n,vector<vector<int>>(n,vector<int>(2,-1)));
        priority_queue<vector<int>,vector<vector<int>>,greater<vector<int>>> pq;
        pq.push({0,1,0,-1});
        pq.push({0,0,0,-1});
        while(!pq.empty()){
            int node=pq.top()[2];
            int color=pq.top()[1];
            int cost=pq.top()[0];
            int source=pq.top()[3];
            pq.pop();
            ans[node]=min(ans[node],cost);
            if(source!=-1)
                visited[source][node][color]=1;
            for(int i=0;i<adj[node].size();i++){
                int neigh=adj[node][i][0];
                int neighColor=adj[node][i][1];
                if(visited[node][neigh][neighColor]!=1 && neighColor!=color){
                    pq.push({cost+1,neighColor,neigh,node});
                }
            }
        }
        for(auto& a:ans){
            if(a==INT_MAX){
                a=-1;
            }
        }
        return ans;
    }
};
























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