bfs.java

// bfs.java
import java.util.*;

public class BFS {
    // Perform BFS on a graph starting from the given source node
    public void bfs(int start, Map<Integer, List<Integer>> graph) {
        Queue<Integer> queue = new LinkedList<>();
        Set<Integer> visited = new HashSet<>();

        queue.add(start);
        visited.add(start);

        while (!queue.isEmpty()) {
            int node = queue.poll();
            System.out.print(node + " ");

            // Explore neighbors
            List<Integer> neighbors = graph.getOrDefault(node, new ArrayList<>());
            for (int neighbor : neighbors) {
                if (!visited.contains(neighbor)) {
                    queue.add(neighbor);
                    visited.add(neighbor);
                }
            }
        }
    }

    public static void main(String[] args) {
        BFS bfs = new BFS();
        
        // Define the graph as an adjacency list
        Map<Integer, List<Integer>> graph = new HashMap<>();
        graph.put(0, Arrays.asList(1, 2));
        graph.put(1, Arrays.asList(0, 3, 4));
        graph.put(2, Arrays.asList(0, 5, 6));
        graph.put(3, Arrays.asList(1));
        graph.put(4, Arrays.asList(1));
        graph.put(5, Arrays.asList(2));
        graph.put(6, Arrays.asList(2));
        
        System.out.println("BFS Traversal starting from node 0:");
        bfs.bfs(0, graph);
    }
}