shortest job first (SJF) also known as | Shortest job next (SJN) or | shortest process next (SPN) scheduling algorithm | c program error free|

#include<stdio.h>

#define S 20

void main()

{

int bt[S],at[S],sum_bt=0,smallest,n,i,j,wt[S],ct[S],p[S],w=-1;

  int sum_turnaround=0,sum_wait=0;

float awt,att;

  printf("Enter no of processes : ");

  scanf("%d",&n);

  for(i=0;i<n;i++)

  {

    printf("Enter burst time and arrival time for proces P%d : ",i+1);

    scanf("%d %d",&bt[i],&at[i]);

    sum_bt+=bt[i];

  }

  printf("\n\nProcess\t|\tBT\t|\tAT\t|\tCT\t| Waiting Time|Turnaround Time\n\n");

  for(j=0;j<sum_bt;)

  {

    smallest=n-1;

    for(i=0;i<n;i++)

    {

      if(at[i]<=j && bt[i]>0 && bt[i]<bt[smallest])

        smallest=i;

    }

    if(smallest==S-1)

    {

      j++;

      continue;

    }

    printf("P[%d] \t|\t %d \t|\t%d\t|\t%d\t|\t%d\t%d\n",smallest+1,bt[smallest],at[smallest],at[smallest]+j+bt[smallest]-at[smallest],j-at[smallest],j+bt[smallest]-at[smallest]);

w++;

p[w]=smallest+1;

ct[w]=(j+bt[smallest]-at[smallest])+at[smallest];

    sum_turnaround+=j+bt[smallest]-at[smallest];

    sum_wait+=j-at[smallest];

    j+=bt[smallest];

    bt[smallest]=0;

  }

  for(i=0;i<n;i++)

  {

  printf("\tp%d",p[i]);

  }

printf("\nat[\t");

  for(i=0;i<n;i++)

  {

  printf("%d\t",ct[i]);

  /*printf("");*/

  }

awt=sum_wait*1.0/n;

att=sum_turnaround*1.0/n;

  printf("\n\n average waiting time = %f",awt);

  printf("\n\n average turnaround time = %f",att);

}