CPT104-lab11-Shortest-Job-First (SJF) scheduling algorithm

 1 //sjf non-preemptive with same arrival time
 2 
 3 #include<stdio.h>
 4 #include<stdlib.h>
 5 #define N 5010
 6 
 7 struct process {
 8     int pid;
 9     int bt;
10     int wt;
11     int tat;
12 };
13 
14 int cmp(const void* a, const void* b) {
15     struct process c = *(struct process*)a;
16     struct process d = *(struct process*)b;
17     return c.bt < d.bt ? 0 : 1;
18 }
19 
20 void main() {
21     puts("Enter total number of processes");
22     int n;
23     scanf("%d", &n);
24     puts("Enter process-id and burst-time for each process
");
25     struct process p[N];
26     for (int i = 0; i < n; i++) scanf("%d%d", &p[i].pid, &p[i].bt);
27     puts("Processes after SJF scheduling...
");
28     qsort(p, n, sizeof(p[0]), cmp);
29     p[0].wt = 0;
30     for (int i = 1; i < n; i++) p[i].wt += p[i - 1].bt + p[i - 1].wt;
31     for (int i = 0; i < n; i++) p[i].tat = p[i].bt + p[i].wt;
32     for (int i = 0; i < n; i++) {
33         printf("Process %d
", p[i].pid);
34         printf("- burst time = %d, waiting time = %d, turnaround time = %d

", p[i].bt, p[i].wt, p[i].tat);
35     }
36     int twt = 0, ttat = p[0].bt;
37     for (int i = 1; i < n; i++) {
38         twt = twt + p[i].wt;
39         ttat = ttat + p[i].tat;
40     }
41     float awt = (float)twt / n;
42     float atat = (float)ttat / n;
43     printf("Average waiting time = %4.2f
", awt);
44     printf("Average turnaround time = %4.2f
", atat);
45 }