queuearray.java

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

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

class queue
{
  int a[],front,back,n;
  
  public queue(int size)
  {
    n=size;
    a=new int [n];
    front=-1;
    back=-1;
  }
  
  public boolean isEmpty()
  {
    return(back==-1);
  } 
   
  public void insert(int x)
  {
    if(isEmpty())
    {
      front++;
      back++;
      a[back]=x;
    }
    else
    {
      back++;
      a[back]=x;
    }
  }

  public void delete()
  {
    if(!isEmpty() && front<=back)
    {
      System.out.println("Element "+a[front]+" deleted");
      front++;
    }
    else
      System.out.println("Queue Empty!");
  }

  public void status()
  {
    System.out.println("Queue contains :"+(back-front)+"elements.\nThey are:");
    for(int i=0;i<=(back-front);i++)
       System.out.print(a[i]+"  ");
  }
        
}
public class queuearray
{
  public static void main(String args[])
  {
    Scanner s=new Scanner(System.in);
    System.out.print("\nEnter the size of queue:");
    int ch,n=s.nextInt();
    queue Q=new queue(n);
     
    do
    {
 
      System.out.println("\n1. Enqueue\n2. Dequeue\n3. Status\n4. Exit");
      System.out.print("Enter choice:");
      ch=s.nextInt();
      switch(ch)
      {
        case 1:
          System.out.print("Enter the element:");
          int x=s.nextInt();
          Q.insert(x);
          break;
        case 2:
          Q.delete();
          break;
        case 3:
          Q.status();
          break;
        case 4:
          break;
        default:
          System.out.println("Invalid choice!");
      }
    }while(ch!=4);
   }
}