Graphs - Level line wise traversal

I/P:

7

8

0 1 10

1 2 10

2 3 10

0 3 10

3 4 10

4 5 10

5 6 10

4 6 10

2

O/P:

Level: 0 --> 2 

Level: 1 --> 1 3 

Level: 2 --> 0  cycle 4 

Level: 3 --> 5 6 

Level: 4 -->  cycle 

Using this we can detect the number of cycle, with the level order line wise traversal

1. Remove

2, Mark

3. Work

4, Add child

package pep.Day40;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Queue;

public class Graphs_Level_Order_Traversal {

    static class Edge {
        int src;
        int nbr;

        Edge(int src, int nbr) {
            this.src = src;
            this.nbr = nbr;
        }
    }

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int vtces = Integer.parseInt(br.readLine());
        ArrayList<Edge>[] graph = new ArrayList[vtces];
        for (int i = 0; i < vtces; i++) {
            graph[i] = new ArrayList<>();
        }

        int edges = Integer.parseInt(br.readLine());
        for (int i = 0; i < edges; i++) {
            String[] parts = br.readLine().split(" ");
            int v1 = Integer.parseInt(parts[0]);
            int v2 = Integer.parseInt(parts[1]);
            graph[v1].add(new Edge(v1, v2));
            graph[v2].add(new Edge(v2, v1));
        }

        int src = Integer.parseInt(br.readLine());
        Queue<Integer> queue = new ArrayDeque<>();
        queue.add(src);
        boolean[] visited = new boolean[vtces];
        int level = 0;
        while (!queue.isEmpty()) {
            int size = queue.size();
            System.out.print("Level: " + level + " --> ");
            for (int i = 0; i < size; i++) {
                int out = queue.remove();        // REMOVE
                if (visited[out]) {
                    System.out.print("cycle");
                    continue;
                }
                visited[out] = true;            // MARK
                System.out.print(out + " ");    // WORK
                for (Edge e : graph[out]) {     // Add CHILD
                    if (!visited[e.nbr])
                        queue.add(e.nbr);
                }

            }
            System.out.println();
            level++;
        }


    }

}