<p>There is a <strong>directed graph</strong> of <code>n</code> colored nodes and <code>m</code> edges. The nodes are numbered from <code>0</code> to <code>n - 1</code>.</p>

<p>You are given a string <code>colors</code> where <code>colors[i]</code> is a lowercase English letter representing the <strong>color</strong> of the <code>i<sup>th</sup></code> node in this graph (<strong>0-indexed</strong>). You are also given a 2D array <code>edges</code> where <code>edges[j] = [a<sub>j</sub>, b<sub>j</sub>]</code> indicates that there is a <strong>directed edge</strong> from node <code>a<sub>j</sub></code> to node <code>b<sub>j</sub></code>.</p>

<p>A valid <strong>path</strong> in the graph is a sequence of nodes <code>x<sub>1</sub> -&gt; x<sub>2</sub> -&gt; x<sub>3</sub> -&gt; ... -&gt; x<sub>k</sub></code> such that there is a directed edge from <code>x<sub>i</sub></code> to <code>x<sub>i+1</sub></code> for every <code>1 &lt;= i &lt; k</code>. The <strong>color value</strong> of the path is the number of nodes that are colored the <strong>most frequently</strong> occurring color along that path.</p>

<p>Return <em>the <strong>largest color value</strong> of any valid path in the given graph, or </em><code>-1</code><em> if the graph contains a cycle</em>.</p>

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

<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet1.png" style="width: 400px; height: 182px;" /></p>

<pre>
<strong>Input:</strong> colors = &quot;abaca&quot;, edges = [[0,1],[0,2],[2,3],[3,4]]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The path 0 -&gt; 2 -&gt; 3 -&gt; 4 contains 3 nodes that are colored <code>&quot;a&quot; (red in the above image)</code>.
</pre>

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

<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/21/leet2.png" style="width: 85px; height: 85px;" /></p>

<pre>
<strong>Input:</strong> colors = &quot;a&quot;, edges = [[0,0]]
<strong>Output:</strong> -1
<strong>Explanation:</strong> There is a cycle from 0 to 0.
</pre>

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

<ul>
	<li><code>n == colors.length</code></li>
	<li><code>m == edges.length</code></li>
	<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>0 &lt;= m &lt;= 10<sup>5</sup></code></li>
	<li><code>colors</code> consists of lowercase English letters.</li>
	<li><code>0 &lt;= a<sub>j</sub>, b<sub>j</sub>&nbsp;&lt; n</code></li>
</ul>
class Solution {
    private: static const int N = 1e5 + 5;
public:

int indegree[N];
int dp[N][26];
int vis[N] , anc[N];
vector<int>gr[N];
// int dfs(int src , int par){
//     vis[src] = 1;
//     for(auto i : gr[src]){
//         if (anc[i]) return false;
//         if (vis[i]) continue;
//         anc[i] = 1;
//         int val = dfs(i , src);
//         anc[i] = 0;
//         if (!val) return false;
//     }
//     return true;
// }
int largestPathValue(string colors, vector<vector<int>>& edges) {
    int n = colors.size();
    vector<int>v;
    for(int i = 0 ; i<n ; i++) v.push_back(colors[i] - 'a');
    for(auto i : edges){
        gr[i[0]].push_back(i[1]);
        indegree[i[1]] ++;
    }
    // for(int i = 0 ; i<n ; i++){
    //     if (!vis[i]) {
    //         anc[i] = 1;
    //         int val = dfs(i , -1);
    //         if (!val) return -1;
    //     }
    // }
    int cnt = 0;
    queue<int>q;
    for(int i = 0 ; i<n ; i++){
        if (!indegree[i]) q.push(i);
    }
    int ans = 0;
    while(!q.empty()){
        int top = q.front();
        q.pop();
        cnt ++;
        // cout<<v[top]<<" ";
        dp[top][v[top]] ++;
        ans = max(ans , dp[top][v[top]]);
        for(auto i : gr[top]){
        indegree[i] --;
        for(int j = 0 ; j<26 ; j++){
            dp[i][j] = max(dp[i][j] , dp[top][j]);
        }
        if (indegree[i] == 0) q.push(i);
        }
    }
    return (cnt == n?ans:-1);
}
};
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