Question

There are n processes in a queue. Each process has name_i and time_i. The round-robin scheduling handles the processes in order. A round-robin scheduler gives each process a quantum (a time slot) and interrupts the process if it is not completed by then. The process is resumed and moved to the end of the queue, then the scheduler handles the next process in the queue.

For example, we have the following queue with the quantum of 100ms.

A(150) - B(80) - C(200) - D(200)

First, process A is handled for 100ms, then the process is moved to the end of the queue with the remaining time (50ms).

B(80) - C(200) - D(200) - A(50)

Next, process B is handled for 80ms. The process is completed with the time stamp of 180ms and removed from the queue.

C(200) - D(200) - A(50)

Your task is to write a program which simulates the round-robin scheduling.

Input

n q
name₁ time₁
name₂ time₂
...
name_n time_n

In the first line the number of processes n and the quantum q are given separated by a single space.

In the following n lines, names and times for the n processes are given. name_i and time_i are separated by a single space.

Output

For each process, prints its name and the time the process finished in order.

Constraints

• 1 ≤ n ≤ 100000
• 1 ≤ q ≤ 1000
• 1 ≤ time_i ≤ 50000
• 1 ≤ length of name_i ≤ 10
• 1 ≤ Sum of time_i ≤ 1000000

Sample Input 1

5 100
p1 150
p2 80
p3 200
p4 350
p5 20

Sample Output 1

p2 180
p5 400
p1 450
p3 550
p4 800

USE JAVA

Answer 1

CODE IN JAVA:

RoundRobin.java file:

import java.util.Scanner;

public class RoundRobin {

   public static void main(String[] args) {

   // creating object to the scanner class
  
       Scanner sc = new Scanner(System.in);
      
       //taking input from the user
      
       System.out.print("Enter the number of processes and quantum:");
      
       int n = sc.nextInt();
      
       int q = sc.nextInt();
  
       int processTime[] = new int[n];
      
       String processName[] = new String[n];
      
       boolean status[] = new boolean[n];
      
       String str= sc.nextLine();
      
       System.out.print("Enter the process name and process time:");
      
       for(int i=0;i<n;i++) {
      
       processName[i]= sc.nextLine();
      
           processTime[i] = sc.nextInt();
          
           status[i] = false;
          
           str= sc.nextLine();
  
       }
  
       //applying round robin algorithm
      
       boolean flag = true;
      
       int totalTime = 0 ;
      
       for(int i=0;i<n;i++) {
      
       if(status[i]) {
      
           flag = true;
      
       }
      
       else {
      
           if(processTime[i]<=q) {
          
               totalTime += processTime[i];
              
               processTime[i] = 0 ;
              
               flag = false;
              
               status[i] = true;
              
               System.out.println(processName[i]+"\t"+totalTime);
          
           }
      
           else {
          
               processTime[i] -= q ;
              
               totalTime += q ;
              
               flag = false;
      
           }
      
       }
      
       if(i==n-1)
      
           i=-1;
      
       for(boolean b:status) {
      
           if(b==false)
      
               flag = false;
      
       }
      
       if(flag)
      
           break;
      
       }
  
   }

}

OUTPUT: