update bfs

Java/Algorithm/SearchingAlgorithm/Breadth-First Search (BFS) Searching .java

@@ -0,0 +1,95 @@
+import java.util.*;
+
+public class Graph {
+    private int V; // Number of vertices
+    private LinkedList<Integer> adj[]; // Adjacency List
+
+    // Constructor
+    Graph(int v) {
+        V = v;
+        adj = new LinkedList[v];
+        for (int i = 0; i < v; ++i)
+            adj[i] = new LinkedList();
+    }
+
+    // Add an edge to the graph
+    void addEdge(int v, int w) {
+        if (v >= 0 && v < V && w >= 0 && w < V) {
+            adj[v].add(w);
+        } else {
+            throw new IllegalArgumentException("Invalid edge: " + v + " -> " + w);
+        }
+    }
+
+    // BFS traversal from a given source s
+    void BFS(int s) {
+        // Mark all the vertices as not visited
+        boolean visited[] = new boolean[V];
+
+        // Create a queue for BFS
+        LinkedList<Integer> queue = new LinkedList<Integer>();
+
+        // Mark the current node as visited and enqueue it
+        visited[s] = true;
+        queue.add(s);
+
+        while (queue.size() != 0) {
+            // Dequeue a vertex from queue and print it
+            s = queue.poll();
+            System.out.print(s + " ");
+
+            // Get all adjacent vertices of the dequeued vertex s.
+            Iterator<Integer> i = adj[s].listIterator();
+            while (i.hasNext()) {
+                int n = i.next();
+                if (!visited[n]) {
+                    visited[n] = true;
+                    queue.add(n);
+                }
+            }
+        }
+    }
+
+    // Driver method to
+    public static void main(String args[]) {
+        Scanner scanner = new Scanner(System.in);
+
+        try {
+            System.out.print("Enter the number of vertices: ");
+            int V = scanner.nextInt();
+            if (V <= 0) {
+                throw new IllegalArgumentException("Number of vertices must be positive.");
+            }
+
+            Graph g = new Graph(V);
+
+            System.out.println("Enter the number of edges: ");
+            int E = scanner.nextInt();
+            if (E < 0) {
+                throw new IllegalArgumentException("Number of edges must be non-negative.");
+            }
+
+            System.out.println("Enter the edges (source destination): ");
+            for (int i = 0; i < E; i++) {
+                int source = scanner.nextInt();
+                int destination = scanner.nextInt();
+                g.addEdge(source, destination);
+            }
+
+            System.out.print("Enter the starting vertex for BFS: ");
+            int startVertex = scanner.nextInt();
+            if (startVertex < 0 || startVertex >= V) {
+                throw new IllegalArgumentException("Starting vertex is out of bounds.");
+            }
+
+            System.out.println("BFS Traversal starting from vertex " + startVertex + ":");
+            g.BFS(startVertex);
+        } catch (InputMismatchException e) {
+            System.out.println("Invalid input. Please enter integers only.");
+        } catch (IllegalArgumentException e) {
+            System.out.println(e.getMessage());
+        } finally {
+            scanner.close();
+        }
+    }
+}