Merge pull request #1 from pojith/pojith-patch-1

Create Breadth-First Search (BFS) Searching.java

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

@@ -0,0 +1,71 @@
+import java.util.*;
+
+public class BFS {
+    private int V; // Number of vertices
+    private LinkedList<Integer> adj[]; // Adjacency list representation of the graph
+
+    public BFS(int v) {
+        V = v;
+        adj = new LinkedList[v];
+        for (int i = 0; i < v; ++i)
+            adj[i] = new LinkedList();
+    }
+
+    // Function to add an edge into the graph
+    void addEdge(int v, int w) {
+        adj[v].add(w);
+    }
+
+    // BFS traversal starting from a given source vertex
+    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<>();
+
+        // Mark the current node as visited and enqueue it
+        visited[s] = true;
+        queue.add(s);
+
+        while (queue.size() != 0) {
+            // Dequeue a vertex from the queue and print it
+            s = queue.poll();
+            System.out.print(s + " ");
+
+            // Get all adjacent vertices of the dequeued vertex s. If an adjacent vertex has not been visited,
+            // then mark it visited and enqueue it
+            Iterator<Integer> i = adj[s].listIterator();
+            while (i.hasNext()) {
+                int n = i.next();
+                if (!visited[n]) {
+                    visited[n] = true;
+                    queue.add(n);
+                }
+            }
+        }
+    }
+
+    public static void main(String args[]) {
+        Scanner scanner = new Scanner(System.in);
+
+        System.out.print("Enter the number of vertices: ");
+        int V = scanner.nextInt();
+
+        BFS graph = new BFS(V);
+
+        System.out.println("Enter the edges (vertex pairs, -1 to stop): ");
+        while (true) {
+            int v1 = scanner.nextInt();
+            if (v1 == -1) break;
+            int v2 = scanner.nextInt();
+            graph.addEdge(v1, v2);
+        }
+
+        System.out.print("Enter the starting vertex for BFS: ");
+        int startVertex = scanner.nextInt();
+
+        System.out.println("Breadth First Traversal starting from vertex " + startVertex + ":");
+        graph.BFS(startVertex);
+    }
+}