Priority Scheduling

 //PROGRAM FOR PRIORITY 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], pt[20], wt[20],ct[20],tat[20]; 
//bt-BURST TIME ;pt-PRIORITY;wt-WAITING TIME; tat-TURN AROUND TIME  
      int temp1, temp2, temp3, count=0,twt=0;//,tat=0;  
      printf("Enter number of processes:");  
      scanf("%d", &n);  
      printf("Enter <ProcessName> <ArrivalTime> <BurstTime> <Priority> :\n");  
 //TAKING INPUT VALUES i.e., PROCESS-NAMES, ARRIVAL-TIMES AND BURST-TIMES  
      for(i=0; i<n; i++)  
           scanf("%s%d%d%d",&pn[i],&at[i],&bt[i],&pt[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 PRIORITY  
                     ( (i==0||count<1)&&(at[i]>at[j]||(at[i]==at[j]&&pt[i]>pt[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 PRIORITY  
                ||  ((ct[i-1]>=at[j]&&pt[i]>pt[j]))// || (ct[i-1]<at[i]&&ct[i-1]>=at[j]))  
                  )  
                     //SWAPPING PROCESSES  
                     {  
           temp1 = bt[i];  
           bt[i] = bt[j];  
           bt[j] = temp1;  
           temp2 = at[i];  
           at[i] = at[j];  
           at[j] = temp2;  
           temp3 = pt[i];  
           pt[i] = pt[j];  
           pt[j] = temp3;  
           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.\tPN\tAT\tBT\tPri\tCT\tWT\tTAT\n");  
      for(i=0; i<n; i++)  
printf("%d\t%s\t%d\t%d\t%d\t%d\t%d\t%d\n",(i+1),pn[i],at[i],bt[i],pt[i],ct[i],wt[i],tat[i]);  
 } //END OF MAIN  
 /* EXAMPLE OUTPUT  
 Enter number of processes:4  
 Enter <ProcessName> <ArrivalTime> <BurstTime> <Priority> :  
 p1 3  2 4  
 p2 2  1 6  
 p3 10 2 3  
 p4 2  3 2  
 S.N.  PN   AT   BT  Pri   CT   WT   TAT  
 1     p4   2    3    2    5    0    3  
 2     p1   3    2    4    7    2    4  
 3     p2   2    1    6    8    5    6  
 4     p3   10   2    3    12   0    2  
 */