srtf (sjf preemptive)

#include <stdio.h>

#define MAX_PROCESSES 100
#define INF 100000 // A large number to represent infinity

int main() {
    int n;
    int pid[MAX_PROCESSES], arrival[MAX_PROCESSES], burst[MAX_PROCESSES], remaining[MAX_PROCESSES];
    int wait[MAX_PROCESSES], turn[MAX_PROCESSES], completion[MAX_PROCESSES];

    // Input number of processes
    printf("Enter number of processes: ");
    scanf("%d", &n);

    // Input arrival time and burst time for each process
    for (int i = 0; i < n; i++) {
        pid[i] = i + 1;
        printf("Enter arrival time for process %d: ", pid[i]);
        scanf("%d", &arrival[i]);
        printf("Enter burst time for process %d: ", pid[i]);
        scanf("%d", &burst[i]);
        remaining[i] = burst[i]; // Initially, remaining time is equal to burst time
    }

    int currentTime = 0, completed = 0;
    int shortest, minRemaining;

    while (completed != n) {
        shortest = -1;
        minRemaining = INF;

        // Find the process with the shortest remaining time among the processes that have arrived
        for (int i = 0; i < n; i++) {
            if (arrival[i] <= currentTime && remaining[i] > 0 && remaining[i] < minRemaining) {
                minRemaining = remaining[i];
                shortest = i;
            }
        }

        if (shortest == -1) {
            currentTime++;
        } else {
            remaining[shortest]--;
            currentTime++;

            if (remaining[shortest] == 0) {
                completed++;
                completion[shortest] = currentTime;
                turn[shortest] = completion[shortest] - arrival[shortest];
                wait[shortest] = turn[shortest] - burst[shortest];
            }
        }
    }

    // Print process information
    printf("PID\tArrival Time\tBurst Time\tWaiting Time\tTurnaround Time\tCompletion Time\n");
    for (int i = 0; i < n; i++) {
        printf("%d\t%d\t\t%d\t\t%d\t\t%d\t\t%d\n",
               pid[i], arrival[i], burst[i], wait[i], turn[i], completion[i]);
    }

    // Calculate and print average waiting and turnaround times
    float totalWait = 0, totalTurnaround = 0;
    for (int i = 0; i < n; i++) {
        totalWait += wait[i];
        totalTurnaround += turn[i];
    }

    printf("Average Waiting Time: %.2f\n", totalWait / n);
    printf("Average Turnaround Time: %.2f\n", totalTurnaround / n);

    return 0;
}