topologicalsort.h

#ifndef topological_h
#define topologicalsort_h

#include<iostream> 
#include <list> 
#include <stack> 
using namespace std; 
  
class Graph 
{ 
    int V;     
  
    list<int> *adj; 

    void topologicalSortUtil(int v, bool visited[], stack<int> &Stack)
    {

        visited[v] = true; 
  
        list<int>::iterator i;

        for (i = adj[v].begin(); i != adj[v].end(); ++i) 
        {
            if (!visited[*i]) topologicalSortUtil(*i, visited, Stack); 
        }
      
        Stack.push(v);
    }

    public:

    Graph(int v)
    {
        V = v;

        adj = new list<int>[V];
    }

    void addEdge(int v, int w) 
    { 
                    
        adj[v].push_back(w);
    }
  
    void topologicalSort()
    {

        stack<int> Stack; 

        bool *visited = new bool[V]; 

        for (int i = 0; i < V; i++) 
        {
            visited[i] = false; 
        }
                   
        for (int i = 0; i < V; i++) 
        {
            if (visited[i] == false) topologicalSortUtil(i, visited, Stack); 
                  
        }

        while (Stack.empty() == false) 
        { 
            cout <<" "<<Stack.top() << " "; 
             Stack.pop(); 
        }
    } 
}; 

#endif