<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) {
        unordered_map<string,vector<string > > adj;
        for(int i=0;i<redEdges.size();i++){
            string from=to_string(redEdges[i][0])+'b';
            string to=to_string(redEdges[i][1])+'r';
            adj[from].push_back(to);  
        }
        for(int i=0;i<blueEdges.size();i++){
            string from=to_string(blueEdges[i][0])+'r';
            string to=to_string(blueEdges[i][1])+'b';
            adj[from].push_back(to);  
        }
        // string src="0";//ultimate source
        string dest=to_string(n-1);//ultimate dset
        // adj[src].push_back("0b");
        // adj[src].push_back("0r");
        adj[to_string(n-1)+"r"].push_back(dest);
        adj[to_string(n-1)+"b"].push_back(dest);
        unordered_map<string,int> dist;
        unordered_map<string,bool> vis;
         dist["0b"]=0;
        dist["0r"]=0;
        vis["0b"]=true;
        vis["0r"]=true;
        
        queue<string> q;
        q.push("0b");
        q.push("0r");

        while(!q.empty()){
            string cur=q.front();
            q.pop();

            for(auto nbr:adj[cur]){
                if(!vis[nbr]){
                    vis[nbr]=1;
                    dist[nbr]=dist[cur]+1;
                    q.push(nbr);
                }
            }
        }
        vector<int> ans(n,-1);
        for(int i=0;i<n;i++) {
            string node_b=to_string(i)+"b";
            string node_r=to_string(i)+"r";

            int val_b=dist.find(node_b)!=dist.end()?dist[node_b]:INT_MAX;
            int val_r=dist.find(node_r)!=dist.end()?dist[node_r]:INT_MAX;
            
            int val=min(val_b, val_r);
            if (val!=INT_MAX) {
                ans[i]=val;
            }
        }

        return ans;

        
    }
};
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