4a.c

// fcfs
#include <stdio.h> 

struct process
{
    int pid, bt, ct, wt, tat;
} p[20];

int main()
{
    int n, i;
    printf("\nEnter the Number of Processes : "); 
    scanf("%d", &n);
    for (i = 0; i < n; i++)
    {
        p[i].pid = i;
        printf("\nEnter the Burst time for Process %d : ", i); scanf("%d", &p[i].bt);
    }
    p[0].ct = 0;
    for (i = 0; i < n; i++)
    {
        p[i].ct = p[i - 1].ct + p[i].bt; p[i].tat = p[i].ct;
    }
    p[0].wt = 0;
    for (i = 0; i < n; i++) 
        p[i].wt = p[i].tat - p[i].bt;
    printf("\nProcess execution order:\n"); for (i = 0; i < n; i++)
    printf("P%d->", p[i].pid);
    printf("\n\tPID\t\tBurst Time\t Turnaround Time\t Waiting Time\n"); 
    for (i = 0; i < n; i++)
        printf("\n\t%d\t\t%d\t\t\t%d\t\t\t%d", p[i].pid, p[i].bt, p[i].tat, p[i].wt); 
    printf("\n");
    float avgtat = 0, avgwt = 0; for (i = 0; i < n; i++)
    {
        avgtat += p[i].tat; avgwt += p[i].wt;
    }
    printf("Average Turn Around Time = %.2f\n", avgtat / n); 
    printf("Average Waiting Time = %.2f\n", avgwt / n);
    return 0;
}