Envío 2549

Código

#include <iostream>
#include<bits/stdc++.h> 
#include <vector>

using namespace std; 

void addEdge(vector<int> adj[], int u, int v){
	adj[u].push_back(v);
}
 

bool isCyclicUtil(vector<int> adj[], int v, bool visited[], bool *recStack) 
{ 
    if(visited[v] == false) 
    { 
        // Mark the current node as visited and part of recursion stack 
        visited[v] = true; 
        recStack[v] = true; 
  
        // Recur for all the vertices adjacent to this vertex 
        vector<int>::iterator i; 
        for(i = adj[v].begin(); i != adj[v].end(); ++i) 
        { 
            if ( !visited[*i] && isCyclicUtil(adj, *i, visited, recStack) ) 
                return true; 
            else if (recStack[*i]) 
                return true; 
        } 
  
    } 
    recStack[v] = false;  // remove the vertex from recursion stack 
    return false; 
} 

bool bfs(vector<int> adj[], int V){
	bool *visited = new bool[V];
	bool *recStack = new bool[V];
	for(int i =0;i<V;i++){
		visited[i] = false;
		recStack[i] = false;
	}
	
	for(int i = 0; i < V; i++) 
        if (isCyclicUtil(adj, i, visited, recStack)) 
            return true; 
  
    return false; 
	
}

int main() {
	int N, M;
	cin >> N;
	cin >> M;
    vector<int> adj[N]; 
    for(int i = 0; i < M ;i++){
    	int u,v;
    	cin >> u;
    	cin >> v;
    	addEdge(adj, u, v); 
	}
	 bool res =  bfs(adj, N);
	 if(res == 1)
    	cout << "Yes" << endl;
    else
    	cout << "No" << endl;
    return 0; 
}