SJF CPU Scheduling Algorithm (Non-Preemptive)

 //PROGRAM FOR SHORTEST-JOB-FIRST(SJF) "CPU SCHEDULING ALGORITHM" WITHOUT PRE_EMPTION  
 #include<stdio.h>  
 #include<conio.h>  
 int main()  
 {  
   int at[10], bt[10], ct[10], wt[10], ta[10], tat[10];  
   //at-ArritvalTime::br-BurstTime::ct-CompletionTime::ta-TemporaryArray  
   //wt-WaitingTime::tat-TurnAroundTime::tn-CurrentTime(TimeNow)  
   int n, i, k, pc=0, pointer = 0, tn =0, c;//pc-ProcessesCompleted  
   char pn[10][10]; //pn-ProcessName  
   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)  
   {  
     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])  
           pointer = k;  
       if(ct[pointer]<0)  
       {  
         tn=tn+bt[pointer];  
         bt[pointer] = 0;  
         ct[pointer] = tn;  
         wt[pointer] = ct[pointer] - ( at[pointer]+ ta[pointer] );  
         tat[pointer] = ct[pointer] - at[pointer];  
         pc++;  
       }  
     }  
   }  
   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;  
 }  
 /* EXAMPLE OUTPUT  
 Enter the number of processes: 6  
 Enter <ProcessName> <ArrivalTime> <BurstTime>  
 p1 3 2  
 p2 6 5  
 p3 1 1  
 p4 6 2  
 p5 15 3  
 p6 20 10  
 PN   AT   BT    CT    WT   TAT  
 p1   3     2     5    0     2  
 p2   6     5     13   2     7  
 p3   1     1     2    0     1  
 p4   6     2     8    0     2  
 p5   15    3    18    0     3  
 p6   20   10    30    0    10  
 */   

//ANOTHER PROGRAM for the same problem

 //PROGRAM FOR SHORTEST-JOB-FIRST(SJF) "CPU SCHEDULING ALGORITHM" WITH NO-PRE_EMPTION & ARRIVAL TIMES  
 #include<stdio.h>  
 #include<string.h>  
 int main(void)  
 {  
 //VARIABLE DECLARATION  
   char pn[20][20], c[20][20]; //PN-PROGRAM NAMES C-A TEMPORARY ARRAY  
      int n,i,j,at[20], bt[20], wt[20],ct[20],tat[20]; //bt-BURST TIME ; wt-WAITING TIME; tat-TURN AROUND TIME  
      int temp1, temp2, count=0,twt=0;//,tat=0;  
      printf("Enter number of processes:");  
      scanf("%d", &n);  
      printf("Enter PN, AT, BT:\n");  
 //TAKING INPUT VALUES i.e., PROCESS-NAMES, ARRIVAL-TIMES AND BURST-TIMES  
      for(i=0; i<n; i++)  
           scanf("%s%d%d",&pn[i],&at[i],&bt[i]);  
 //SCHEDULING THE PROCESSES ACCORDING TO SJF  
   for(i=0 ; i<n; i++)  
   {  
           for(j=i+1; j<n; j++)  
       if (  
         //IF THERE IS NO PROCESS IN MAIN MEMORY,  
           //SORT PROCESSES ACCORDING TO ARRIVAL TIMES &  
           //IF WE GOT PROCESSES WITH SAME ARRIVAL TIME SORT THEM BY BURST TIMES  
                     ( (i==0||count<1)&&(at[i]>at[j]||(at[i]==at[j]&&bt[i]>bt[j])) )  
         //IF WE GOT ONLY ONE PROCESS IN MAIN MEMORY AFTER COMPLETION OF THE CURRENT PROCESS  
                ||      (count == 1 && ct[i-1]>=at[j])  
         //IF WE GOT MORE THAN ONE PROCESS IN MAIN MEMORY, SORT THEM BY BURST TIMES  
                ||      ((ct[i-1]>=at[j]&&bt[i]>bt[j]))// || (ct[i-1]<at[i]&&ct[i-1]>=at[j]))  
                  )  
                     //SWAPPING PROCESSES  
                     {  
           temp1 = bt[i];  
           temp2 = at[i];  
           bt[i] = bt[j];  
           at[i] = at[j];  
           bt[j] = temp1;  
           at[j] = temp2;  
           strcpy(c[i],pn[i]);  
           strcpy(pn[i],pn[j]);  
           strcpy(pn[j],c[i]);  
         }  
     if(i==0 || count<1)  
       ct[i] = at[i] + bt[i];  
     else  
       ct[i] = ct[i-1] + bt[i];  
     wt[i] = ct[i] - (at[i] + bt[i]);  
     tat[i] = ct[i] - at[i];  
     count = 0 ;  
     for(j=i+1; j<n; j++)  
       if(ct[i]>=at[j])  
         count++;  
   }  
 //PRINTING THE VALUES AFTER ALL PREOCESSES COMPLETED  
      printf("S.N.\tProcess-Name\tArrival-Time\tBurst-Time\tCT\tWT\tTAT\n");  
      for(i=0; i<n; i++)  
           printf("%d\t\t%s\t\t%d\t\t%d\t%d\t%d\t%d\n",(i+1),pn[i],at[i],bt[i],ct[i],wt[i],tat[i]);  
 } //END OF MAIN  
 /* EXAMPLE OUTPUT  
 Enter number of processes:6  
 Enter PN, AT, BT:  
 p1 3 2  
 p2 6 5  
 p3 1 1  
 p4 6 2  
 p5 15 3  
 p6 20 10  
 S.N.  Process-Name  Arrival-Time  Burst-Time   CT   WT   TAT  
 1        p3       1        1    2    0    1  
 2        p1       3        2    5    0    2  
 3        p4       6        2    8    0    2  
 4        p2       6        5    13   2    7  
 5        p5       15       3    18   0    3  
 6        p6       20       10   30   0    10  
 */