First Come First Served

S
A
```# Implementation of First Come First Served scheduling algorithm
# In this Algorithm we just care about the order that the processes arrived
# without carring about their duration time
# https://en.wikipedia.org/wiki/Scheduling_(computing)#First_come,_first_served
from __future__ import annotations

def calculate_waiting_times(duration_times: list[int]) -> list[int]:
"""
This function calculates the waiting time of some processes that have a
specified duration time.
Return: The waiting time for each process.
>>> calculate_waiting_times([5, 10, 15])
[0, 5, 15]
>>> calculate_waiting_times([1, 2, 3, 4, 5])
[0, 1, 3, 6, 10]
>>> calculate_waiting_times([10, 3])
[0, 10]
"""
waiting_times = [0] * len(duration_times)
for i in range(1, len(duration_times)):
waiting_times[i] = duration_times[i - 1] + waiting_times[i - 1]
return waiting_times

def calculate_turnaround_times(
duration_times: list[int], waiting_times: list[int]
) -> list[int]:
"""
This function calculates the turnaround time of some processes.
Return: The time difference between the completion time and the
arrival time.
Practically waiting_time + duration_time
>>> calculate_turnaround_times([5, 10, 15], [0, 5, 15])
[5, 15, 30]
>>> calculate_turnaround_times([1, 2, 3, 4, 5], [0, 1, 3, 6, 10])
[1, 3, 6, 10, 15]
>>> calculate_turnaround_times([10, 3], [0, 10])
[10, 13]
"""
return [
duration_time + waiting_times[i]
for i, duration_time in enumerate(duration_times)
]

def calculate_average_turnaround_time(turnaround_times: list[int]) -> float:
"""
This function calculates the average of the turnaround times
Return: The average of the turnaround times.
>>> calculate_average_turnaround_time([0, 5, 16])
7.0
>>> calculate_average_turnaround_time([1, 5, 8, 12])
6.5
>>> calculate_average_turnaround_time([10, 24])
17.0
"""
return sum(turnaround_times) / len(turnaround_times)

def calculate_average_waiting_time(waiting_times: list[int]) -> float:
"""
This function calculates the average of the waiting times
Return: The average of the waiting times.
>>> calculate_average_waiting_time([0, 5, 16])
7.0
>>> calculate_average_waiting_time([1, 5, 8, 12])
6.5
>>> calculate_average_waiting_time([10, 24])
17.0
"""
return sum(waiting_times) / len(waiting_times)

if __name__ == "__main__":
# process id's
processes = [1, 2, 3]

# ensure that we actually have processes
if len(processes) == 0:
print("Zero amount of processes")
raise SystemExit(0)

# duration time of all processes
duration_times = [19, 8, 9]

# ensure we can match each id to a duration time
if len(duration_times) != len(processes):
print("Unable to match all id's with their duration time")
raise SystemExit(0)

# get the waiting times and the turnaround times
waiting_times = calculate_waiting_times(duration_times)
turnaround_times = calculate_turnaround_times(duration_times, waiting_times)

# get the average times
average_waiting_time = calculate_average_waiting_time(waiting_times)
average_turnaround_time = calculate_average_turnaround_time(turnaround_times)

# print all the results
print("Process ID\tDuration Time\tWaiting Time\tTurnaround Time")
for i, process in enumerate(processes):
print(
f"{process}\t\t{duration_times[i]}\t\t{waiting_times[i]}\t\t"
f"{turnaround_times[i]}"
)
print(f"Average waiting time = {average_waiting_time}")
print(f"Average turn around time = {average_turnaround_time}")
```