Graph Algorithms Implementation in C#

using System;
using System.Collections.Generic;

public class Graph
{
    // Dictionary to store adjacency list of the graph
    private Dictionary<int, List<int>> adjList = new Dictionary<int, List<int>>();

    public void AddEdge(int src, int dest)
    {
        if (!adjList.ContainsKey(src))
        {
            adjList[src] = new List<int>();
        }
        if (!adjList.ContainsKey(dest))
        {
            adjList[dest] = new List<int>();
        }
        adjList[src].Add(dest);
        adjList[dest].Add(src);
    }

    // Method to perform Breadth-First Search from a given starting vertex
    public List<int> Bfs(int start)
    {
        var visited = new HashSet<int>();
        var queue = new Queue<int>();
        var result = new List<int>();

        queue.Enqueue(start); // Start the BFS with the starting vertex

        while (queue.Count > 0)
        {
            int node = queue.Dequeue(); // Remove the vertex at the front of the queue
            if (!visited.Contains(node))
            {
                visited.Add(node);
                result.Add(node);
                foreach (var neighbor in adjList[node])
                {
                    // Add unvisited neighbors to the queue
                    if (!visited.Contains(neighbor))
                    {
                        queue.Enqueue(neighbor);
                    }
                }
            }
        }

        return result;
    }

    public static void Main(string[] args)
    {
        Graph graph = new Graph();
        // Create graph by adding edges between vertices
        graph.AddEdge(0, 1);
        graph.AddEdge(0, 2);
        graph.AddEdge(1, 2);
        graph.AddEdge(2, 0); // multi-edge between 0 and 2
        graph.AddEdge(2, 3);
        graph.AddEdge(3, 3);

        Console.WriteLine("BFS traversal starting from node 2:");
        // Perform BFS starting from vertex 2 and print the result
        Console.WriteLine(string.Join(", ", graph.Bfs(2)));
    }
}