fcfs.java

import java.util.*;
 
public class FCFS {
	public static void main(String args[])
	{
		Scanner sc = new Scanner(System.in);
		System.out.println("enter no of process: ");
		int n = sc.nextInt();
		int pid[] = new int[n];   
		int ar[] = new int[n];     
		int bt[] = new int[n];   
		int ct[] = new int[n];     
		int ta[] = new int[n];     
		int wt[] = new int[n];     
		int temp;
		float avgwt=0,avgta=0;
 
		for(int i = 0; i < n; i++)
		{
			System.out.println("enter process " + (i+1) + " arrival time: ");
			ar[i] = sc.nextInt();
			System.out.println("enter process " + (i+1) + " brust time: ");
			bt[i] = sc.nextInt();
			pid[i] = i+1;
		}
 
		//sorting according to arrival times
		for(int i = 0 ; i <n; i++)
		{
			for(int  j=0;  j < n-(i+1) ; j++)
			{
				if( ar[j] > ar[j+1] )
				{
					temp = ar[j];
					ar[j] = ar[j+1];
					ar[j+1] = temp;
					temp = bt[j];
					bt[j] = bt[j+1];
					bt[j+1] = temp;
					temp = pid[j];
					pid[j] = pid[j+1];
					pid[j+1] = temp;
				}
			}
		}
		
		
		for(int  i = 0 ; i < n; i++)
		{
			if( i == 0)
			{	
				ct[i] = ar[i] + bt[i];
			}
			else
			{
				if( ar[i] > ct[i-1])
				{
					ct[i] = ar[i] + bt[i];
				}
				else
					ct[i] = ct[i-1] + bt[i];
			}
			ta[i] = ct[i] - ar[i] ;         
			wt[i] = ta[i] - bt[i] ;         
			avgwt += wt[i] ;               
			avgta += ta[i] ;              
		}
		
		System.out.println("\npid  arrival  brust  complete turn waiting");
		for(int  i = 0 ; i< n;  i++)
		{
			System.out.println(pid[i] + "  \t " + ar[i] + "\t" + bt[i] + "\t" + ct[i] + "\t" + ta[i] + "\t"  + wt[i] ) ;
		}
		sc.close();
		System.out.println("\naverage waiting time: "+ (avgwt/n));     
		System.out.println("average turnaround time:"+(avgta/n));    
	}
}