DirectedGraph::isAcyclic

#include "HKUAL_graph.h"
#include <iostream>
using namespace std;
using namespace HKUAL;

int main(){
    DirectedGraph<string> g;
    g.addVertex("A");
    g.addVertex("B");
    g.addVertex("C");
    g.addVertex("D");
    g.addVertex("E");
    g.addEdge("A","B");
    g.addEdge("A","C");
    g.addEdge("B","C");
    g.addEdge("B","D");
    g.addEdge("C","D");
    g.addEdge("E","A");

    if (g.isAcyclic())
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
    
    return 0;
}