c program to implement non preemptive priority scheduling algorithm

1#include<stdio.h>
2 
3int main()
4{
5    int bt[20],p[20],wt[20],tat[20],pr[20],i,j,n,total=0,pos,temp,avg_wt,avg_tat;
6    printf("Enter Total Number of Process:");
7    scanf("%d",&n);
8 
9    printf("\nEnter Burst Time and Priority\n");
10    for(i=0;i<n;i++)
11    {
12        printf("\nP[%d]\n",i+1);
13        printf("Burst Time:");
14        scanf("%d",&bt[i]);
15        printf("Priority:");
16        scanf("%d",&pr[i]);
17        p[i]=i+1;           //contains process number
18    }
19 
20    //sorting burst time, priority and process number in ascending order using selection sort
21    for(i=0;i<n;i++)
22    {
23        pos=i;
24        for(j=i+1;j<n;j++)
25        {
26            if(pr[j]<pr[pos])
27                pos=j;
28        }
29 
30        temp=pr[i];
31        pr[i]=pr[pos];
32        pr[pos]=temp;
33 
34        temp=bt[i];
35        bt[i]=bt[pos];
36        bt[pos]=temp;
37 
38        temp=p[i];
39        p[i]=p[pos];
40        p[pos]=temp;
41    }
42 
43    wt[0]=0;	//waiting time for first process is zero
44 
45    //calculate waiting time
46    for(i=1;i<n;i++)
47    {
48        wt[i]=0;
49        for(j=0;j<i;j++)
50            wt[i]+=bt[j];
51 
52        total+=wt[i];
53    }
54 
55    avg_wt=total/n;      //average waiting time
56    total=0;
57 
58    printf("\nProcess\t    Burst Time    \tWaiting Time\tTurnaround Time");
59    for(i=0;i<n;i++)
60    {
61        tat[i]=bt[i]+wt[i];     //calculate turnaround time
62        total+=tat[i];
63        printf("\nP[%d]\t\t  %d\t\t    %d\t\t\t%d",p[i],bt[i],wt[i],tat[i]);
64    }
65 
66    avg_tat=total/n;     //average turnaround time
67    printf("\n\nAverage Waiting Time=%d",avg_wt);
68    printf("\nAverage Turnaround Time=%d\n",avg_tat);
69 
70	return 0;
71}
72