queueimp.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 static int member;
  public int data;
  public node link;
  public node()
  {
    member++;
  }
}

class queue
{
  
  node front,back;
  
  public queue()
  {
    front=null;
    back=null;
  }
    
  public boolean isempty()
  {
   if(back==null)
         return true;
   return false;
  }
  
   
  public void insert(int data)
  {
    if(isempty())
    {
       node temp=new node();
       temp.data=data;
       temp.link=front;
       front=temp;
       back=front;
    }
  
    else
    {
       node temp=new node();
       temp.data=data;
       temp.link=back;
       back=temp;
    }
  }
  
  public int delete()
  {
   
    if(!isempty())
    {
      int val=back.data;
      back=back.link;
      front.member--;
      return val;
    }
    else
     {
       System.out.println("\nQueue is empty!\n");
       return 0;
     }
       
  }

  public void listqueue()
  {
    node iterator;
    iterator=back;
    while(iterator!=null)
    {
      
      System.out.print(iterator.data+"  ");
      iterator=iterator.link;
    }

  }
  public void status()
  {
   System.out.println("Queue has currently "+front.member);
  }
}


public class queueimp  
{

  public static void main(String args[])
  {
    queue q1=new queue();
    int ch=0;
    Scanner s=new Scanner(System.in);
    do    
    {
       System.out.println("\n\n1. Check status \n2.Insert\n3.delete\n4.List the queue\n5.Exit");
       System.out.print("Enter your choice:");
       ch=s.nextInt();
       if(ch==1)
         q1.status();
       else if(ch==2)
            {
              System.out.println("Enter the element:");
              int id=s.nextInt();
              q1.insert(id);
            }
            else if(ch==3)
                 {
                   System.out.println("Element "+q1.delete()+" Deleted, Queue is now:");
                   q1.listqueue();
                 }
                 else if(ch==4)
                     q1.listqueue();
     }
     while(ch!=5);
  }
}