2360. Longest Cycle in a Graph

class Solution {
public:
    stack<int> st;
    vector<bool> vis;
    int cnt = 0;
    void dfs( int node, vector<int> adj[]){
        cnt++;
        vis[node] = true;
        for(int i:adj[node]){
            if(vis[i]==false){
                dfs( i, adj );
            }
        }
        st.push(node); 
    }
    
    int longestCycle(vector<int>& edges) { 
        int n=edges.size();   
        vis.resize(n,false);
        vector<int> adj[n],adjT[n];
        for(int i=0;i<n;i++){
            if(edges[i]!=-1){
                adj[i].push_back(edges[i]);
                adjT[edges[i]].push_back(i);
            }
        }
        for(int i=0;i<n;i++){
            if(!vis[i]){
                dfs(i,adj);
            }
        }
        vis.clear();
        vis.resize(n,false); 
		
        int ans = 0;
        while(st.size()){
            int node = st.top();
             st.pop();
            if(vis[node]) continue; 
            cnt = 0;
            dfs(node,adjT);
            ans = max(ans,cnt);
        }
        return (ans==1?-1:ans);
    }
};