toposort in C#

using System;
using System.Collections.Generic;
 
class Graph {
 
    // No. of vertices
    private int V;
 
    // Adjacency List as ArrayList
    // of ArrayList's
    private List<List<int> > adj;
 
    // Constructor
    Graph(int v)
    {
        V = v;
        adj = new List<List<int> >(v);
        for (int i = 0; i < v; i++)
            adj.Add(new List<int>());
    }
 
    // Function to add an edge into the graph
    public void AddEdge(int v, int w) { adj[v].Add(w); }
 
    // A recursive function used by topologicalSort
    void TopologicalSortUtil(int v, bool[] visited,
                             Stack<int> stack)
    {
 
        // Mark the current node as visited.
        visited[v] = true;
 
        // Recur for all the vertices
        // adjacent to this vertex
        foreach(var vertex in adj[v])
        {
            if (!visited[vertex])
                TopologicalSortUtil(vertex, visited, stack);
        }
 
        // Push current vertex to
        // stack which stores result
        stack.Push(v);
    }
 
    // The function to do Topological Sort.
    // It uses recursive topologicalSortUtil()
    void TopologicalSort()
    {
        Stack<int> stack = new Stack<int>();
 
        // Mark all the vertices as not visited
        var visited = new bool[V];
 
        // Call the recursive helper function
        // to store Topological Sort starting
        // from all vertices one by one
        for (int i = 0; i < V; i++) {
            if (visited[i] == false)
                TopologicalSortUtil(i, visited, stack);
        }
 
        // Print contents of stack
        foreach(var vertex in stack)
        {
            Console.Write(vertex + " ");
        }
    }
 
    // Driver code
    public static void Main(string[] args)
    {
 
        // Create a graph given
        // in the above diagram
        Graph g = new Graph(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);
 
        Console.WriteLine("Following is a Topological "
                          + "sort of the given graph");
 
        // Function Call
        g.TopologicalSort();
    }
}