TopoLogicalSort

#include <bits/stdc++.h>
using namespace std;
class Edge
{
public:
	int source;
	int neighbour;
	int weight;
	void add(int source, int neighbour, int weight)
	{
		this->source = source;
		this->neighbour = neighbour;
		this->weight = weight;
	}
};
void topologicalSort(std::vector<Edge> v[], int source, bool *vis, stack<int>&st)
{
	vis[source] = true;
	for (auto E : v[source])
	{
		if (vis[E.neighbour] == false)
		{
			topologicalSort(v, E.neighbour, vis, st);
		}
	}
	st.push(source);
}
int main()
{
	int vertices;
	cin >> vertices;
	vector<Edge> adj[vertices];
	int edge; cin >> edge;
	for (int i = 0; i < edge; i++)
	{
		int v1, v2, weight = 1;
		cin >> v1 >> v2;
		Edge p1;
		p1.add(v1, v2, weight);
		adj[v1].push_back(p1);
	}
	bool vis[vertices] = {false};
	stack<int>st;
	for (int i = 0; i < vertices; i++)
	{
		if (vis[i] == false)
		{
			topologicalSort(adj, i, vis, st);
		}
	}
	while (st.size())
	{
		cout << st.top() << " ";
		st.pop();
	}
	return 0;
}