SJF CPU Scheduling Algorithm (Preemptive)

//PROGRAM FOR SHORTEST-JOB-FIRST(SJF) "CPU SCHEDULING ALGORITHM" WITH PRE_EMPTION
 #include<stdio.h>  
 #include<conio.h>  
 int main()  
 {  
   int n,at[10], bt[10], ct[10], wt[10], tn =0, c, ta[10],tat[10];  
   //at-ArritvalTime::br-BurstTime::ct-CompletionTime::ta-TemporaryArray  
   //wt-WaitingTime::tat-TurnAroundTime::tn-CurrentTime(TimeNow)  
  // int i, j, k, tot, pc=0, pointer = 0, lp=-1;//lp-Last-executedProcess  
   int i, k, tot, pc=0, pointer = 0, lp=-1;//lp-Last-executedProcess  
   char pn[10][10];  
   printf("Enter the number of processes: ");  
   scanf("%d",&n);  
   printf("Enter <ProcessName> <ArrivalTime> <BurstTime>\n");  
   for(i=0;i<n;i++)  
     scanf("%s%d%d",&pn[i],&at[i],&bt[i]);  
   for(i=0; i<n; i++)  
   {  
       ct[i] = -1;  
       ta[i] = bt[i];  
   }  
   while(pc!=n)  
   {  
     k=0;  
     c = 0;  
     for(i=0; i<n; i++)  
     {  
       if(ct[i]<0 && at[i]<=tn)  
         c++;  
     }  
     if(c==0)  
       tn++;  
     else  
     {  
       pointer = 0;  
       while(at[pointer]>tn || ct[pointer]>0)  
         pointer++;  
       for(k=pointer+1; k<n; k++)  
         if( (at[k]<=tn && ct[k]<0) &&  
           ( (bt[pointer]==bt[k] && k==lp) || bt[pointer]>bt[k] ) )  
             pointer = k;  
       if(ct[pointer]<0)  
       {  
         bt[pointer]--;  
         tn++;  
         if(bt[pointer]==0)  
         {  
           ct[pointer] = tn;  
           wt[pointer] = ct[pointer] - ( at[pointer]+ ta[pointer] );  
           tat[pointer] = ct[pointer] - at[pointer];  
           pc++;  
         }  
       }  
       lp = pointer;  
     }  
   }  
   printf("\nPN\tAT\tBT\tCT\tWT\tTAT\n");  
   for(i=0;i<n;i++)  
     printf("%s\t%d\t%d\t%d\t%d\t%d\n",pn[i],at[i],ta[i],ct[i],wt[i],tat[i]);  
   return 0;  
 }  
 /* SAMPLE OUTPUT  
 Enter the number of processes: 6  
 Enter <ProcessName> <ArrivalTime> <BurstTime>  
 p1 3 1  
 p2 1 4  
 p3 10 6  
 p4 25 10  
 p5 1 3  
 p6 12 3  
 PN   AT    BT   CT   WT   TAT  
 p1   3     1     5    1     2  
 p2   1     4     9    4     8  
 p3   10    6    19    3     9  
 p4   25   10    35    0    10  
 p5   1     3    4     0     3  
 p6   12    3    15    0     3  
 */