49 lines
1.4 KiB
Python
49 lines
1.4 KiB
Python
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import sys
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def sjf_preemptive(processes, n):
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remaining_time = [bt for _, _, bt in processes]
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complete = 0
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t = 0
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minm = sys.maxsize
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shortest = 0
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finish_time = 0
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check = False
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waiting_time = [0] * n
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turnaround_time = [0] * n
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while complete != n:
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for j in range(n):
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if processes[j][1] <= t and remaining_time[j] < minm and remaining_time[j] > 0:
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minm = remaining_time[j]
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shortest = j
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check = True
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if not check:
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t += 1
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continue
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remaining_time[shortest] -= 1
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minm = remaining_time[shortest] if remaining_time[shortest] > 0 else sys.maxsize
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if remaining_time[shortest] == 0:
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complete += 1
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check = False
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finish_time = t + 1
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waiting_time[shortest] = finish_time - processes[shortest][2] - processes[shortest][1]
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if waiting_time[shortest] < 0:
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waiting_time[shortest] = 0
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t += 1
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for i in range(n):
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turnaround_time[i] = processes[i][2] + waiting_time[i]
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print("\nSJF (Preemptive) Scheduling:")
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for i, process in enumerate(processes):
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print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
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# Input: Process ID, Arrival Time, Burst Time
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processes = [[1, 0, 8], [2, 1, 4], [3, 2, 9], [4, 3, 5]]
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sjf_preemptive(processes, len(processes))
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