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package os_project;

import java.text.DecimalFormat;
import java.util.InputMismatchException;
import java.util.Scanner;

public class sample {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        DecimalFormat format = new DecimalFormat ("##.##");

    	System.out.println("====================================================================================");
		System.out.println("\t\tP R I O R I T Y   S C H E D U L I N G   A L G O R I T H M");
		System.out.println("====================================================================================");
		
		int job = 0;
		boolean processInput = false;
		
		//ask for number of processes
		while (!processInput) {
			//try catch to repeat while loop until user enters a valid number of processes
			try {
				System.out.print("\nEnter the number of processes: ");
				job = sc.nextInt();
				processInput = true;
			} catch (InputMismatchException e) {
				System.out.println("Please enter whole numbers only.");
				sc.nextLine();
			}
		}

        double Burst[] = new double[job];
        int Priority[] = new int[job];

        	//ask for burst time and priority number of each process
        	for (int i = 0; i < job; i++) {
        		boolean burstInput = false;
        		boolean priorityInput = false; 
        		System.out.println("\n------------------------------------- Process " + (i+1) + " ------------------------------------");
        		
        		while (!burstInput) {
        		try {
        			System.out.print("\nBurst Time:\t");
        			Burst[i] = sc.nextDouble();
        			burstInput = true;
        		} catch (InputMismatchException e) {
        			System.out.println("\nPlease enter NUMBERS only!\n");
        			sc.nextLine(); //read invalid burst to not have an infinite loop
        			}
        		}
        		while (!priorityInput) {
        		try {
        			System.out.print("Priority:\t");
        			Priority[i] = sc.nextInt();
        			priorityInput = true; //continue the iteration
        		} catch (InputMismatchException e) {
        			System.out.println("\nPlease enter WHOLE NUMBERS only!\n");
        			sc.nextLine(); //read invalid burst to not have an infinite loop
        		}
        		}
        }

        //temporary array to store sorted priority Numbers and compare it to the unsorted priority array
        int P1[] = new int[job];

        //copy Priority elements to P1
        for ( int i = 0; i < job; i++) {
            P1[i] = Priority[i];
        }

        //bubble sort, sorts elements in P1 in ascending order
        for (int i = 0; i < job; i++) {
            for (int j = 0; j < job-1; j++) {
                if(Priority[j] > Priority[j+1]) {
                    int temp = Priority[j];
                    Priority[j] = Priority[j+1];
                    Priority[j+1] = temp;
                }
            }
        }

        double wait = 0;
        double turnTable = 0;
        double waitingTime[] = new double[job];
        double turnaround[] = new double[job];
        float totalWait = 0;
        float totalTurn = 0;
        int k = 0;
        int l = 0;

        System.out.format("%63s","\n====================================================================================\n");
        System.out.format("%15s %15s %15s %15s %18s", "Process", "Priority No.", "Burst Time", "Waiting Time", "Turnaround Time\n");
        System.out.format("%63s","====================================================================================\n");

        //Iterate on each of the priorities 
        for (int i = 0; i < job; i++) {
        	// Skip duplicate
            if (i > 0 && Priority[i] == Priority[i-1]) {
                continue;
            }
        	// Iterate on all job
            for (int j = 0; j < job; j++) {

                if (Priority[i] == P1[j]) {
                    turnTable += Burst[j];
                    System.out.format("%12d %13d %17.2f %15.2f %15.2f\n", (j+1), P1[j], Burst[j], wait, turnTable);
                    
                    waitingTime[k] = wait;
                    totalWait += wait;
                    wait += Burst[j];

                    turnaround[k] = waitingTime[k] + Burst[j];
                    totalTurn += turnaround[l];
                }
            }
        }

        System.out.println("\n\tAVERAGE WAITING TIME: " + format.format(totalWait/job) + "\t\tAVERAGE TURNAROUND TIME: " + format.format(totalTurn/job));

        System.out.format("%63s","====================================================================================\n");
        
        System.out.print("\nWould you like to restart the program?\nPress [Y] to restart or ANY KEY to terminate:\t ");
        String restart = sc.next();
        
        if (restart.equals('Y')) {
        	main(null);
        } else {
        	System.out.println("\nProgram terminated. Thanks for using the program!");
        }
    }

}