TopologicalSort.cpp

#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); 

public: 
	Graph(int V);


	void addEdge(int v, int w); 


	void topologicalSort(); 
}; 

Graph::Graph(int V) 
{ 
	this->V = V; 
	adj = new list<int>[V]; 
} 

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

void Graph::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); 
} 

void Graph::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(); 
	} 
} 
int main() 
{ 
	Graph g(6); 
	g.addEdge(5, 2); 
	g.addEdge(5, 0); 
	g.addEdge(4, 0); 
	g.addEdge(4, 1); 
	g.addEdge(2, 3); 
	g.addEdge(3, 1); 

	cout << "Topological Sort:"; 
	g.topologicalSort(); 

	return 0; 
}