queuelinked.java

many simple java programs like classic algorithems to do search and few data structure implimentatio

import java.io.*;
import java.util.Scanner;

class node
{
  public node link;
  public int data;
}

class queue
{
  public node front,rear;
  public int count;
  public queue()
  {
    front=null;
    rear=null;
    count=0;
  }  

  public boolean isEmpty()
  {
    return(front==null);
  }

  public void enqueue(int x)
  {
    
     if(isEmpty())
     {
       node temp=new node();
       temp.data=x;
       front=temp;
       rear=temp;
       count++;
     }
     else
     {
       node temp=new node();
       temp.data=x;
       rear.link=temp;
       rear=temp;
       count++;
     }
   }
  public void dequeue()
  {
   if(!isEmpty())
     {
       System.out.println("The element "+front.data+" has been removed from queue!");
       front=front.link;
       count--;
     }
   else
      System.out.println("Queue is Empty!");
   }
 
   public void listQ()
   {
     node iterator=front;
      while(iterator!=null)
        {
          System.out.print(iterator.data+ "   ");
          iterator=iterator.link;
        }
    }
   public void status()
   {
     if(!isEmpty())
     {
       System.out.println("\nStatus: Queue contains "+count+" elements");
       System.out.print("Front : "+front.data+"\nRear :"+rear.data);
     }
     else
       System.out.println("Queue is empty!");
   }
}

public class queuelinked
{
  public static void main(String args[])
  {
   queue Q=new queue();
   Scanner s=new Scanner(System.in);
   int ch;
   do
   {   
      System.out.println("\nCurrent Queue:");
      Q.listQ();
      System.out.println("\n1. Insert\n2. Delete \n3. Status \n4. Exit");
      ch=s.nextInt();
      switch(ch)
      {
       case 1:
          System.out.print("\nEnter data to be inserted:");
          Q.enqueue(s.nextInt());
          break;
       case 2:
          System.out.print("\nDeleting...\n");
          Q.dequeue();
          break;
       case 3:
          Q.status();
          break;
       case 4:
          System.out.println("Exiting...");
          System.exit(0);
       default:
          System.out.println("Invalid choice!");
       } 
   }
    while(ch!=4);
   }
}