Program for FCFS CPU Scheduling | Set 1

Given n processes with their burst times, the task is to find average waiting time and average turn around time using FCFS scheduling algorithm. 
First in, first out (FIFO), also known as first come, first served (FCFS), is the simplest scheduling algorithm. FIFO simply queues processes in the order that they arrive in the ready queue. 
In this, the process that comes first will be executed first and next process starts only after the previous gets fully executed. 
Here we are considering that arrival time for all processes is 0.

How to compute below times in Round Robin using a program?

1. Completion Time: Time at which process completes its execution.
2. Turn Around Time: Time Difference between completion time and arrival time. Turn Around Time = Completion Time – Arrival Time
3. Waiting Time(W.T): Time Difference between turn around time and burst time. 
   Waiting Time = Turn Around Time – Burst Time

In this post, we have assumed arrival times as 0, so turn around and completion times are same.

Implementation:

1-  Input the processes along with their burst time (bt).
2-  Find waiting time (wt) for all processes.
3-  As first process that comes need not to wait so 
    waiting time for process 1 will be 0 i.e. wt[0] = 0.
4-  Find waiting time for all other processes i.e. for
     process i -> 
       wt[i] = bt[i-1] + wt[i-1] .
5-  Find turnaround time = waiting_time + burst_time 
    for all processes.
6-  Find average waiting time = 
                 total_waiting_time / no_of_processes.
7-  Similarly, find average turnaround time = 
                 total_turn_around_time / no_of_processes.

C++

// C++ program for implementation of FCFS
// scheduling
#include<iostream>
using namespace std;

// Function to find the waiting time for all
// processes
void findWaitingTime(int processes[], int n,
                          int bt[], int wt[])
{
    // waiting time for first process is 0
    wt[0] = 0;

    // calculating waiting time
    for (int  i = 1; i < n ; i++ )
        wt[i] =  bt[i-1] + wt[i-1] ;
}

// Function to calculate turn around time
void findTurnAroundTime( int processes[], int n,
                  int bt[], int wt[], int tat[])
{
    // calculating turnaround time by adding
    // bt[i] + wt[i]
    for (int  i = 0; i < n ; i++)
        tat[i] = bt[i] + wt[i];
}

//Function to calculate average time
void findavgTime( int processes[], int n, int bt[])
{
    int wt[n], tat[n], total_wt = 0, total_tat = 0;

    //Function to find waiting time of all processes
    findWaitingTime(processes, n, bt, wt);

    //Function to find turn around time for all processes
    findTurnAroundTime(processes, n, bt, wt, tat);

    //Display processes along with all details
    cout << "Processes  "<< " Burst time  "
         << " Waiting time  " << " Turn around time\n";

    // Calculate total waiting time and total turn
    // around time
    for (int  i=0; i<n; i++)
    {
        total_wt = total_wt + wt[i];
        total_tat = total_tat + tat[i];
        cout << "   " << i+1 << "\t\t" << bt[i] <<"\t    "
            << wt[i] <<"\t\t  " << tat[i] <<endl;
    }

    cout << "Average waiting time = "
         << (float)total_wt / (float)n;
    cout << "\nAverage turn around time = "
         << (float)total_tat / (float)n;
}

// Driver code
int main()
{
    //process id's
    int processes[] = { 1, 2, 3};
    int n = sizeof processes / sizeof processes[0];

    //Burst time of all processes
    int  burst_time[] = {10, 5, 8};

    findavgTime(processes, n,  burst_time);
    return 0;
}

C

// C program for implementation of FCFS
// scheduling
#include<stdio.h>
// Function to find the waiting time for all
// processes
void findWaitingTime(int processes[], int n,
                          int bt[], int wt[])
{
    // waiting time for first process is 0
    wt[0] = 0;

    // calculating waiting time
    for (int  i = 1; i < n ; i++ )
        wt[i] =  bt[i-1] + wt[i-1] ;
}

// Function to calculate turn around time
void findTurnAroundTime( int processes[], int n,
                  int bt[], int wt[], int tat[])
{
    // calculating turnaround time by adding
    // bt[i] + wt[i]
    for (int  i = 0; i < n ; i++)
        tat[i] = bt[i] + wt[i];
}

//Function to calculate average time
void findavgTime( int processes[], int n, int bt[])
{
    int wt[n], tat[n], total_wt = 0, total_tat = 0;

    //Function to find waiting time of all processes
    findWaitingTime(processes, n, bt, wt);

    //Function to find turn around time for all processes
    findTurnAroundTime(processes, n, bt, wt, tat);

    //Display processes along with all details
    printf("Processes   Burst time   Waiting time   Turn around time\n");

    // Calculate total waiting time and total turn
    // around time
    for (int  i=0; i<n; i++)
    {
        total_wt = total_wt + wt[i];
        total_tat = total_tat + tat[i];
        printf("   %d ",(i+1));
        printf("       %d ", bt[i] );
        printf("       %d",wt[i] );
        printf("       %d\n",tat[i] );
    }
    int s=(float)total_wt / (float)n;
    int t=(float)total_tat / (float)n;
    printf("Average waiting time = %d",s);
    printf("\n");
    printf("Average turn around time = %d ",t);
}

// Driver code
int main()
{
    //process id's
    int processes[] = { 1, 2, 3};
    int n = sizeof processes / sizeof processes[0];

    //Burst time of all processes
    int  burst_time[] = {10, 5, 8};

    findavgTime(processes, n,  burst_time);
    return 0;
}
// This code is contributed by Shivi_Aggarwal

Java

// Java program for implementation of FCFS
// scheduling

import java.text.ParseException;

class GFG {

    // Function to find the waiting time for all
    // processes
    static void findWaitingTime(int processes[], int n,
            int bt[], int wt[]) {
        // waiting time for first process is 0
        wt[0] = 0;

        // calculating waiting time
        for (int i = 1; i < n; i++) {
            wt[i] = bt[i - 1] + wt[i - 1];
        }
    }

    // Function to calculate turn around time
    static void findTurnAroundTime(int processes[], int n,
            int bt[], int wt[], int tat[]) {
        // calculating turnaround time by adding
        // bt[i] + wt[i]
        for (int i = 0; i < n; i++) {
            tat[i] = bt[i] + wt[i];
        }
    }

    //Function to calculate average time
    static void findavgTime(int processes[], int n, int bt[]) {
        int wt[] = new int[n], tat[] = new int[n];
        int total_wt = 0, total_tat = 0;

        //Function to find waiting time of all processes
        findWaitingTime(processes, n, bt, wt);

        //Function to find turn around time for all processes
        findTurnAroundTime(processes, n, bt, wt, tat);

        //Display processes along with all details
        System.out.printf("Processes Burst time Waiting"
                       +" time Turn around time\n");

        // Calculate total waiting time and total turn
        // around time
        for (int i = 0; i < n; i++) {
            total_wt = total_wt + wt[i];
            total_tat = total_tat + tat[i];
            System.out.printf(" %d ", (i + 1));
            System.out.printf("     %d ", bt[i]);
            System.out.printf("     %d", wt[i]);
            System.out.printf("     %d\n", tat[i]);
        }
        float s = (float)total_wt /(float) n;
        int t = total_tat / n;
        System.out.printf("Average waiting time = %f", s);
        System.out.printf("\n");
        System.out.printf("Average turn around time = %d ", t);
    }

    // Driver code
    public static void main(String[] args) throws ParseException {
        //process id's
        int processes[] = {1, 2, 3};
        int n = processes.length;

        //Burst time of all processes
        int burst_time[] = {10, 5, 8};

        findavgTime(processes, n, burst_time);

    }
}
// This code is contributed by 29ajaykumar

Python 3

# Python3 program for implementation
# of FCFS scheduling

# Function to find the waiting
# time for all processes
def findWaitingTime(processes, n,
                    bt, wt):

    # waiting time for
    # first process is 0
    wt[0] = 0

    # calculating waiting time
    for i in range(1, n ):
        wt[i] = bt[i - 1] + wt[i - 1]

# Function to calculate turn
# around time
def findTurnAroundTime(processes, n,
                       bt, wt, tat):

    # calculating turnaround
    # time by adding bt[i] + wt[i]
    for i in range(n):
        tat[i] = bt[i] + wt[i]

# Function to calculate
# average time
def findavgTime( processes, n, bt):

    wt = [0] * n
    tat = [0] * n
    total_wt = 0
    total_tat = 0

    # Function to find waiting
    # time of all processes
    findWaitingTime(processes, n, bt, wt)

    # Function to find turn around
    # time for all processes
    findTurnAroundTime(processes, n,
                       bt, wt, tat)

    # Display processes along
    # with all details
    print( "Processes Burst time " +
                  " Waiting time " +
                " Turn around time")

    # Calculate total waiting time
    # and total turn around time
    for i in range(n):

        total_wt = total_wt + wt[i]
        total_tat = total_tat + tat[i]
        print(" " + str(i + 1) + "\t\t" +
                    str(bt[i]) + "\t " +
                    str(wt[i]) + "\t\t " +
                    str(tat[i]))

    print( "Average waiting time = "+
                   str(total_wt / n))
    print("Average turn around time = "+
                     str(total_tat / n))

# Driver code
if __name__ =="__main__":

    # process id's
    processes = [ 1, 2, 3]
    n = len(processes)

    # Burst time of all processes
    burst_time = [10, 5, 8]

    findavgTime(processes, n, burst_time)

# This code is contributed
# by ChitraNayal

C#

// C# program for implementation of FCFS
// scheduling
using System;

class GFG
{

    // Function to find the waiting time for all
    // processes
    static void findWaitingTime(int []processes, int n,
                                int []bt, int[] wt)
    {
        // waiting time for first process is 0
        wt[0] = 0;

        // calculating waiting time
        for (int i = 1; i < n; i++)
        {
            wt[i] = bt[i - 1] + wt[i - 1];
        }
    }

    // Function to calculate turn around time
    static void findTurnAroundTime(int []processes, int n,
            int []bt, int []wt, int []tat) {
        // calculating turnaround time by adding
        // bt[i] + wt[i]
        for (int i = 0; i < n; i++)
        {
            tat[i] = bt[i] + wt[i];
        }
    }

    // Function to calculate average time
    static void findavgTime(int []processes, int n, int []bt)
    {
        int []wt = new int[n];
        int []tat = new int[n];
        int total_wt = 0, total_tat = 0;

        //Function to find waiting time of all processes
        findWaitingTime(processes, n, bt, wt);

        //Function to find turn around time for all processes
        findTurnAroundTime(processes, n, bt, wt, tat);

        //Display processes along with all details
        Console.Write("Processes Burst time Waiting"
                    +" time Turn around time\n");

        // Calculate total waiting time and total turn
        // around time
        for (int i = 0; i < n; i++)
        {
            total_wt = total_wt + wt[i];
            total_tat = total_tat + tat[i];
            Console.Write(" {0} ", (i + 1));
            Console.Write("     {0} ", bt[i]);
            Console.Write("     {0}", wt[i]);
            Console.Write("     {0}\n", tat[i]);
        }
        float s = (float)total_wt /(float) n;
        int t = total_tat / n;
        Console.Write("Average waiting time = {0}", s);
        Console.Write("\n");
        Console.Write("Average turn around time = {0} ", t);
    }

    // Driver code
    public static void Main(String[] args)
    {
        // process id's
        int []processes = {1, 2, 3};
        int n = processes.Length;

        // Burst time of all processes
        int []burst_time = {10, 5, 8};

        findavgTime(processes, n, burst_time);
    }
}

// This code contributed by Rajput-Ji

Javascript

<script>

    // JavaScript program for implementation of FCFS
   // scheduling


   // Function to find the waiting time for all
  // processes
    function findWaitingTime(processes,n,bt,wt)
    {
        // waiting time for first process is 0
        wt[0] = 0;

        // calculating waiting time
        for (let i = 1; i < n; i++) {
            wt[i] = bt[i - 1] + wt[i - 1];
        }
    }

    function findTurnAroundTime(processes,n,bt,wt,tat)
    {
        // calculating turnaround time by adding
        // bt[i] + wt[i]
        for (let i = 0; i < n; i++) {
            tat[i] = bt[i] + wt[i];
        }
    }

    function findavgTime(processes,n,bt)
    {
        let wt = new Array(n), tat = new Array(n);
        for(let i=0;i<n;i++)
        {
            wt[i]=0;
            tat[i]=0;
        }
        let total_wt = 0, total_tat = 0;

        //Function to find waiting time of all processes
        findWaitingTime(processes, n, bt, wt);

        //Function to find turn around time for all processes
        findTurnAroundTime(processes, n, bt, wt, tat);

        //Display processes along with all details
        document.write("Processes Burst time Waiting"
                       +" time Turn around time<br>");

        // Calculate total waiting time and total turn
        // around time
        for (let i = 0; i < n; i++) {
            total_wt = total_wt + wt[i];
            total_tat = total_tat + tat[i];
            document.write("    ", (i + 1)+" ");
            document.write("     "+  bt[i]+" ");
            document.write("     "+ wt[i]);
            document.write("     "+ tat[i]+"<br>");
        }
        let s = total_wt / n;
        let t = Math.floor(total_tat / n);
        document.write("Average waiting time = "+ s);
        document.write("<br>");
        document.write("Average turn around time = ", t+" ");
    }

    let processes=[1,2,3];
    let  n = processes.length;

    let burst_time=[10,5,8];
    findavgTime(processes, n, burst_time);

    // This code is contributed by rag2127

</script>

Output:

Processes  Burst time  Waiting time  Turn around time    //The Output is Wrong please correct it
 1        10     0         10
 2        5     10         15
 3        8     15         23
Average waiting time = 8.33333
Average turn around time = 16

Using OOPS.

C++

#include <bits/stdc++.h>
using namespace std;

class Process {
private:
    int at;
    int bt;
    int ct;
    int tat;
    int wt;
    int pid;

public:
    int& operator[](string var)
    {
        if (var == "at")
            return at;
        if (var == "bt")
            return bt;
        if (var == "ct")
            return ct;
        if (var == "tat")
            return tat;
        if (var == "wt")
            return wt;
        return pid;
    }

    void update_after_ct()
    {
        tat = ct - at;
        wt = tat - bt;
    }

    void display()
    {
        printf("%d\t%d\t%d\t%d\t%d\t%d\n", pid, at, bt, ct,
               tat, wt);
    }
};

float average(vector<Process> P, string var)
{
    int total = 0;
    for (auto temp : P) {
        total += temp[var];
    }
    return (float)total / P.size();
}

int main()
{
    /*
    Input description.
    First line contains an integer n
    the next n lines contains 2 space separated integers
    containing values for arrival time and burst time for
    example:
    2
    0 3
    1 2
    */
    int n;
    cin >> n;
    int counter = 0;
    vector<Process> P(n);
    for (Process& temp : P) {
        temp["id"] = counter++;
        cin >> temp["at"] >> temp["bt"];
    }
    sort(P.begin(), P.end(),
         [](Process first, Process second) {
             return first["at"] < second["at"];
         });
    printf("pid\tat\tbt\tct\ttat\twt\n");
    P[0]["ct"] = P[0]["at"] + P[0]["bt"];
    P[0].update_after_ct();
    P[0].display();
    for (int i = 1; i < P.size(); i++) {
        if (P[i]["at"] < P[i - 1]["ct"]) {
            P[i]["ct"] = P[i - 1]["ct"] + P[i]["bt"];
        }
        else {
            printf("curr['at'] : %d, prev['ct'] : %d\n",
                   P[i]["at"], P[i - 1]["ct"]);
            P[i]["ct"] = P[i]["at"] + P[i]["bt"];
        }
        P[i].update_after_ct();
        P[i].display();
    }

    printf("Average waiting time : %f\n", average(P, "wt"));
    return 0;
}

Java

import java.util.*;

public class Main {

    // Process class to represent a process
    static class Process {
        private int at; // arrival time
        private int bt; // burst time
        private int ct; // completion time
        private int tat; // turn around time
        private int wt; // waiting time
        private int pid; // process ID

        // Getter method to get a variable value of the process
        public int getVar(String var) {
            if (var.equals("at"))
                return at;
            if (var.equals("bt"))
                return bt;
            if (var.equals("ct"))
                return ct;
            if (var.equals("tat"))
                return tat;
            if (var.equals("wt"))
                return wt;
            return pid;
        }

        // Setter method to set a variable value of the process
        public void setVar(String var, int value) {
            if (var.equals("at"))
                at = value;
            else if (var.equals("bt"))
                bt = value;
            else if (var.equals("ct"))
                ct = value;
            else if (var.equals("tat"))
                tat = value;
            else if (var.equals("wt"))
                wt = value;
            else
                pid = value;
        }

        // Update the turn around time and waiting time after completion
        public void updateAfterCt() {
            tat = ct - at;
            wt = tat - bt;
        }

        // Display the process details
        public void display() {
            System.out.printf("%d\t%d\t%d\t%d\t%d\t%d\n", pid, at, bt, ct, tat, wt);
        }
    }

    // Calculate the average of a variable value for all processes
    public static float average(ArrayList<Process> P, String var) {
        int total = 0;
        for (Process temp : P) {
            total += temp.getVar(var);
        }
        return (float) total / P.size();
    }

    public static void main(String[] args) {
        /*
        Input description.
        First line contains an integer n
        the next n lines contains 2 space separated integers
        containing values for arrival time and burst time for
        example:
        2
        0 3
        1 2
        */
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int counter = 0;
        ArrayList<Process> P = new ArrayList<Process>(n);
        // Create a process object for each input and add to the process list
        for (int i = 0; i < n; i++) {
            Process temp = new Process();
            temp.setVar("pid", counter++);
            temp.setVar("at", sc.nextInt());
            temp.setVar("bt", sc.nextInt());
            P.add(temp);
        }
        // Sort the process list by arrival time
        Collections.sort(P, new Comparator<Process>() {
            public int compare(Process first, Process second) {
                return first.getVar("at") - second.getVar("at");
            }
        });
        System.out.println("pid\tat\tbt\tct\ttat\twt");
        // Calculate completion time and display the details of the first process
        P.get(0).setVar("ct", P.get(0).getVar("at") + P.get(0).getVar("bt"));
        P.get(0).updateAfterCt();
        P.get(0).display();
        // Calculate completion time and display the details of the remaining processes
       for (int i = 1; i < P.size(); i++) {
           // Loop through the remaining processes
        if (P.get(i).getVar("at") < P.get(i - 1).getVar("ct")) {
            // If the process arrives before the previous process completes
            P.get(i).setVar("ct", P.get(i - 1).getVar("ct") + P.get(i).getVar("bt"));
            // Calculate completion time as the completion time of previous process plus its burst time
        } else {
            // If the process arrives after the previous process completes
            System.out.printf("curr['at'] : %d, prev['ct'] : %d\n\n", P.get(i).getVar("at"),
                    P.get(i - 1).getVar("ct"));
            P.get(i).setVar("ct", P.get(i).getVar("at") + P.get(i).getVar("bt"));
            // Calculate completion time as the arrival time plus its burst time
        }
        P.get(i).updateAfterCt(); // Update the turnaround time and waiting time for the current process
        P.get(i).display(); // Display the details of the current process
    }

    System.out.printf("Average waiting time : %f\n", average(P, "wt"));
    sc.close(); // Close the scanner
}
}

Javascript

class Process {
  constructor() {
    this.at = 0;
    this.bt = 0;
    this.ct = 0;
    this.tat = 0;
    this.wt = 0;
    this.pid = 0;
  }

  update_after_ct() {
    this.tat = this.ct - this.at;
    this.wt = this.tat - this.bt;
  }

  display() {
    console.log(`${this.pid}\t${this.at}\t${this.bt}\t${this.ct}\t${this.tat}\t${this.wt}`);
  }
}

function average(P, varName) {
  let total = 0;
  for (let i = 0; i < P.length; i++) {
    total += P[i][varName];
  }
  return total / P.length;
}

function main() {
  /*
  Input description.
  First line contains an integer n
  the next n lines contains 2 space separated integers
  containing values for arrival time and burst time for
  example:
  2
  0 3
  1 2
  */
  const readline = require("readline");
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });

  rl.question("", (n) => {
    const P = new Array(parseInt(n)).fill(null).map(() => new Process());
    let counter = 0;
    rl.on("line", (line) => {
      const [at, bt] = line.trim().split(" ");
      P[counter]["pid"] = counter++;
      P[counter - 1]["at"] = parseInt(at);
      P[counter - 1]["bt"] = parseInt(bt);

      if (counter == P.length) {
        rl.close();
      }
    });

    rl.on("close", () => {
      P.sort((first, second) => first["at"] - second["at"]);

      console.log("pid\tat\tbt\tct\ttat\twt");
      P[0]["ct"] = P[0]["at"] + P[0]["bt"];
      P[0].update_after_ct();
      P[0].display();

      for (let i = 1; i < P.length; i++) {
        if (P[i]["at"] < P[i - 1]["ct"]) {
          P[i]["ct"] = P[i - 1]["ct"] + P[i]["bt"];
        } else {
          console.log(
            `curr['at'] : ${P[i]["at"]}, prev['ct'] : ${P[i - 1]["ct"]}`
          );
          P[i]["ct"] = P[i]["at"] + P[i]["bt"];
        }
        P[i].update_after_ct();
        P[i].display();
      }

      console.log(`Average waiting time : ${average(P, "wt")}`);
    });
  });
}

main();

C#

using System;
using System.Collections.Generic;

class Process
{
    private int at;
    private int bt;
    private int ct;
    private int tat;
    private int wt;
    private int pid;

    public int this[string var]
    {
        get
        {
            if (var == "at")
                return at;
            if (var == "bt")
                return bt;
            if (var == "ct")
                return ct;
            if (var == "tat")
                return tat;
            if (var == "wt")
                return wt;
            return pid;
        }
        set
        {
            if (var == "at")
                at = value;
            else if (var == "bt")
                bt = value;
            else if (var == "ct")
                ct = value;
            else if (var == "tat")
                tat = value;
            else if (var == "wt")
                wt = value;
            else
                pid = value;
        }
    }

    public void UpdateAfterCt()
    {
        tat = ct - at;
        wt = tat - bt;
    }

    public void Display()
    {
        Console.WriteLine("{0}\t{1}\t{2}\t{3}\t{4}\t{5}",
            pid, at, bt, ct, tat, wt);
    }
}

class Program
{
    static float Average(List<Process> P, string var)
    {
        int total = 0;
        foreach (var temp in P)
        {
            total += temp[var];
        }
        return (float)total / P.Count;
    }

    static void Main()
    {
        /*
        Input description.
        First line contains an integer n
        the next n lines contains 2 space separated integers
        containing values for arrival time and burst time for
        example:
        2
        0 3
        1 2
        */
        int n = int.Parse(Console.ReadLine());
        int counter = 0;
        var P = new List<Process>(n);
        for (int i = 0; i < n; i++)
        {
            var temp = new Process();
            temp["id"] = counter++;
            var line = Console.ReadLine().Split();
            temp["at"] = int.Parse(line[0]);
            temp["bt"] = int.Parse(line[1]);
            P.Add(temp);
        }
        P.Sort((first, second) => first["at"].CompareTo(second["at"]));
        Console.WriteLine("pid\tat\tbt\tct\ttat\twt");
        P[0]["ct"] = P[0]["at"] + P[0]["bt"];
        P[0].UpdateAfterCt();
        P[0].Display();
        for (int i = 1; i < P.Count; i++)
        {
            if (P[i]["at"] < P[i - 1]["ct"])
            {
                P[i]["ct"] = P[i - 1]["ct"] + P[i]["bt"];
            }
            else
            {
                Console.WriteLine("curr['at'] : {0}, prev['ct'] : {1}",
                    P[i]["at"], P[i - 1]["ct"]);
                P[i]["ct"] = P[i]["at"] + P[i]["bt"];
            }
            P[i].UpdateAfterCt();
            P[i].Display();
        }
        Console.WriteLine("Average waiting time : {0}", Average(P, "wt"));
    }
}

Python3

class processes:
    def __init__(self, id, at, bt, ct):
        self.id = id
        self.at = at
        self.bt = bt
        self.ct = ct
        self.tat = self.ct-self.at
        self.wt = self.tat-self.bt

    def get(self):
        print(f"{self.id}\t{self.at}\t{self.bt}\t{self.ct}\t{self.tat}\t{self.wt}")

    def turnaround(self):
        return self.tat

    def waiting(self):
        return self.wt


num = int(input("Enter the Number of Processes:"))
l = []
ct = 0

for i in range(num):

    print(f'Process {i+1}')
    at = int(input("Enter the Arrival Time:-"))
    bt = int(input("Enter the Burst Time:-"))
    if (len(l) == 0):
        ct = bt
        l.append(processes(i, at, bt, ct))
    else:
        ct += bt
        l.append(processes(i, at, bt, ct))

    print("\n")
avg_tat = 0
avg_wat = 0
print("PID\tAT\tBT\tCT\tTAT\tWT")
for process in l:
    process.get()

for process in l:
    avg_tat += process.turnaround()
    avg_wat += process.waiting()
print(f"Avg_turnaround:{avg_tat/num}\nAvg_Waitingtime:{avg_wat/num}")

# pid at bt
# 0 0 5
# 1 2 3
# 2 6 2
# 3 7 3

 PID     AT      BT      CT      TAT     WT
0       0       10      10      10      0
1       10      5       15      5       0
2       15      8       23      8       0
Avg_turnaround:7.666666666666667
Avg_Waitingtime:0.0

Important Points:

1. Non-preemptive
2. Average Waiting Time is not optimal
3. Cannot utilize resources in parallel : Results in Convoy effect (Consider a situation when many IO bound processes are there and one CPU bound process. The IO bound processes have to wait for CPU bound process when CPU bound process acquires CPU. The IO bound process could have better taken CPU for some time, then used IO devices).