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SPOS - Shortest Remaining Time First [SRTF] Program

Shortest Remaining Time First Program

Code :

import java.util.Scanner;
public class SRTFScheduling {
 public static boolean allZeros(int[][] processes) {
 for (int[] data: processes) {
 if (data[2] != 0) {
 return false;
 }
 }
 return true;
 }
 public static int findShortestProcessIndex(int time, int[][] processes) {
 int lowest = Integer.MAX_VALUE;
 int lowestIdx = -1;
 for (int i = 0; i < processes.length; i++) {
 if (processes[i][1] > time || processes[i][2] == 0) {
 continue;
 }
 if (processes[i][2] < lowest) {
 lowest = processes[i][2];
 lowestIdx = i;
 }
 }
 return lowestIdx;
 }
public static float calcAvg(int[] arr) {
 int sum = 0;
 for (int j : arr) {
 sum += j;
 }
 return (float) sum/arr.length;
 }
 public static void main(String[] args) {
 Scanner myScanner = new Scanner(System.in);
 System.out.print("Enter total number of processes: ");
 int totalNumProcesses = myScanner.nextInt();
 int[][] processes = new int[totalNumProcesses][3];
 int[] burstTimesCopy = new int[totalNumProcesses];
 for (int i = 0; i < totalNumProcesses; i++) {
 System.out.print("Enter Process id: ");
 processes[i][0] = myScanner.nextInt();
 System.out.print("Enter Arrival Time: ");
 processes[i][1] = myScanner.nextInt();
 System.out.print("Enter Burst Time: ");
 processes[i][2] = myScanner.nextInt();
 burstTimesCopy[i] = processes[i][2];
 }
 int[] waitingTimes = new int[totalNumProcesses];
 int[] turnAroundTimes = new int[totalNumProcesses];
 int time = 0;
 boolean isDone;
 while(true) {
 isDone = allZeros(processes);
 if (isDone) {
 break;
 }
 int spIdx = findShortestProcessIndex(time, processes);
 if (spIdx == -1) {
 time++;
 continue;
 }
 processes[spIdx][2] -= 1;
 for (int i = 0; i < processes.length; i++) {
 if (i != spIdx && processes[i][2] != 0) {
 waitingTimes[i]++;
 }
 }
 time++;
 }
 for (int i = 0; i < processes.length; i++) {
 waitingTimes[i] -= processes[i][1];
 turnAroundTimes[i] = waitingTimes[i] + burstTimesCopy[i];
 }
 float avgWaitingTime = calcAvg(waitingTimes);
 float avgTurnAroundTime = calcAvg(turnAroundTimes);
 System.out.format("%4s%4s%4s%4s%4s\n", "pid", "at", "bt", "wt", "tat");
 for (int i = 0; i < totalNumProcesses; i++) {
 System.out.format("%4d%4d%4d%4d%4d\n", processes[i][0], processes[i][1],
burstTimesCopy[i], waitingTimes[i], turnAroundTimes[i]);
 }
 System.out.println("The average waiting time is: " + avgWaitingTime);
 System.out.println("The average turnaround time is: " + avgTurnAroundTime);
 }
}

Output :



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