fcfs.c

#include <stdio.h>
#include <stdlib.h>

void calculateWaitingTime(int n, int arrival[], int burst[], int waiting[]) {
    int completion[n];
    completion[0] = arrival[0] + burst[0];
    waiting[0] = 0;

    for (int i = 1; i < n; i++) {
        if (arrival[i] > completion[i - 1]) {
            completion[i] = arrival[i] + burst[i];
        } else {
            completion[i] = completion[i - 1] + burst[i];
        }
        waiting[i] = completion[i] - arrival[i] - burst[i];
        if (waiting[i] < 0) waiting[i] = 0;
    }
}

void calculateTurnaroundTime(int n, int arrival[], int burst[], int waiting[], int turnaround[]) {
    for (int i = 0; i < n; i++)
        turnaround[i] = waiting[i] + burst[i];
}

void displayResults(int n, int pid[], int arrival[], int burst[], int waiting[], int turnaround[]) {
    float total_waiting = 0, total_turnaround = 0;
    printf("\nPID\tArrival\tBurst\tWaiting\tTurnaround\n");
    for (int i = 0; i < n; i++) {
        total_waiting += waiting[i];
        total_turnaround += turnaround[i];
        printf("P%d\t%d\t%d\t%d\t%d\n", pid[i], arrival[i], burst[i], waiting[i], turnaround[i]);
    }
    printf("\nAverage Waiting Time: %.2f", total_waiting / n);
    printf("\nAverage Turnaround Time: %.2f\n", total_turnaround / n);
}

void displayGanttChart(int n, int pid[], int arrival[], int burst[]) {
    printf("\nGantt Chart:\n");
    
    // Top border of the Gantt chart
    printf(" ");
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < burst[i]; j++) printf("--");
        printf(" ");
    }
    printf("\n|");

    // Process sequence in the Gantt chart
    int time = arrival[0];
    for (int i = 0; i < n; i++) {
        if (arrival[i] > time) {
            printf(" Idle |");
            time = arrival[i];
        }
        for (int j = 0; j < burst[i] - 1; j++) printf(" ");
        printf("P%d", pid[i]);
        for (int j = 0; j < burst[i] - 1; j++) printf(" ");
        printf("|");
        time += burst[i];
    }

    // Bottom border of the Gantt chart
    printf("\n ");
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < burst[i]; j++) printf("--");
        printf(" ");
    }

    // Timeline below the Gantt chart
    printf("\n%d", arrival[0]);
    time = arrival[0];
    for (int i = 0; i < n; i++) {
        if (arrival[i] > time) {
            printf("    %d", arrival[i]);
            time = arrival[i];
        }
        for (int j = 0; j < burst[i]; j++) printf("  ");
        time += burst[i];
        printf("%d", time);
    }
    printf("\n");
}

int main() {
    int n;
    printf("Enter number of processes: ");
    scanf("%d", &n);

    int *arrival = (int *)malloc(n * sizeof(int));
    int *burst = (int *)malloc(n * sizeof(int));
    int *waiting = (int *)malloc(n * sizeof(int));
    int *turnaround = (int *)malloc(n * sizeof(int));
    int *pid = (int *)malloc(n * sizeof(int)); // Array to store process IDs

    for (int i = 0; i < n; i++) {
        printf("Enter arrival time and burst time for process %d: ", i + 1);
        scanf("%d %d", &arrival[i], &burst[i]);
        pid[i] = i + 1; // Assign process IDs (P1, P2, ...)
    }

    // Sort processes by arrival time (if not already sorted)
    for (int i = 0; i < n - 1; i++) {
        for (int j = 0; j < n - i - 1; j++) {
            if (arrival[j] > arrival[j + 1]) {
                // Swap arrival times
                int temp = arrival[j];
                arrival[j] = arrival[j + 1];
                arrival[j + 1] = temp;

                // Swap burst times
                temp = burst[j];
                burst[j] = burst[j + 1];
                burst[j + 1] = temp;

                // Swap process IDs
                temp = pid[j];
                pid[j] = pid[j + 1];
                pid[j + 1] = temp;
            }
        }
    }

    calculateWaitingTime(n, arrival, burst, waiting);
    calculateTurnaroundTime(n, arrival, burst, waiting, turnaround);
    displayResults(n, pid, arrival, burst, waiting, turnaround);
    displayGanttChart(n, pid, arrival, burst);

    free(arrival);
    free(burst);
    free(waiting);
    free(turnaround);
    free(pid);
    return 0;
}