Add CPU Scheduling Algorithm: FCFS

DIRECTORY.md

@@ -178,6 +178,9 @@
   * [Volume Conversions](conversions/volume_conversions.py)
   * [Weight Conversion](conversions/weight_conversion.py)
 
+## CPU Scheduling Algorithms
+  * [FCFS](cpu_scheduling_algorithms/fcfs.py)
+
 ## Data Structures
   * Arrays
     * [Equilibrium Index In Array](data_structures/arrays/equilibrium_index_in_array.py)

cpu_scheduling_algorithms/fcfs.py

@@ -0,0 +1,67 @@
+"""
+Simple Implementation of the FCFS CPU scheduling algorithm
+FCFS is a non-preemptive CPU scheduling algorithm that
+schedules processes based on their arrival time.
+https://www.geeksforgeeks.org/program-for-fcfs-cpu-scheduling-set-1/
+Author: [Madhav Goyal](https://github.com/mdhvg)
+"""
+
+
+def fcfs(processes: list[tuple[int, int, int]]) -> None:
+    """
+    Function to implement the FCFS CPU scheduling algorithm
+
+    processes: list of tuples where each tuple contains the
+    process_id, arrival_time and burst_time of each process
+    """
+    n = len(processes)
+    processes.sort(key=lambda x: x[1])
+    waiting_times = [0] * n
+    total_waiting_time = 0
+
+    for i in range(1, n):
+        waiting_times[i] = processes[i - 1][2] + waiting_times[i - 1]
+        total_waiting_time += waiting_times[i]
+
+    print(f"Average Waiting Time: {total_waiting_time / n}")
+
+    """
+    Printing the Gantt Chart for the processes in the FCFS order
+    The - and * symbols are used to represent the burst time and
+    idle time respectively for each process.
+    """
+    last_burst = 0
+    for i in range(n):
+        print("-" * last_burst, end="")
+        print("*", end="")
+        last_burst = processes[i][2]
+    print("-" * last_burst, end="")
+    print("\n", end="")
+
+    last_burst = 0
+    for i in range(n):
+        print(" " * last_burst, end="")
+        print(f"{processes[i][0]}", end="")
+        last_burst = processes[i][2]
+    print("\n", end="")
+
+
+def main():
+    """
+    Main function to demonstrate the FCFS CPU scheduling algorithm
+    pass an array of (process_id, arrival_time, burst_time) to fcfs
+    >>> processes = [(1, 0, 3), (2, 1, 5), (3, 2, 2), (4, 3, 7), (5, 2, 2)]
+    >>> fcfs(processes)
+    Average Waiting Time: 6.6
+    *---*-----*--*--*-------
+    1   2     3  5  4
+    """
+    processes = [(1, 0, 3), (2, 1, 5), (3, 2, 2), (4, 3, 7), (5, 2, 2)]
+    fcfs(processes)
+
+
+if __name__ == "__main__":
+    main()
+    import doctest
+
+    doctest.testmod()