Program to implement SRTF Scheduling algorithm

    
/* Aim: To implement SRTF Scheduling algorithm
             Author: Rahul kumar */
#include <stdio.h>
#define max 100

int main(){
  int n,AT[max],WT[max],ET[max],TAT[max],CT[max],PID[max],RT[max],i,min,j,temp,maxCT;
  double avg_WT=0,avg_TAT=0,thrpt;
  printf("Please enter number of processes\n");
  scanf("%d",&n);
  if(n>max){
    printf("Limit exceeded.");
  }
  else if(n<1){
    printf("No process exist or negative input.");
  }
  else{
    for(i=0;i< n;i++){
      printf("Enter details for process %d:\n",i+1);
      printf("Arrival Time: ");
      scanf("%d",&AT[i]);
      printf("Execution Time: ");
      scanf("%d",&ET[i]);
      PID[i]=i+1;
    }
       //sorting for arrival time
     for(i=0;i< -1;i++){
      min=i;
      for(j=i+1;j< n;j++){
        if(AT[j]< AT[min]){
          min=j;
        } 
      }
      temp=AT[i];
      AT[i]=AT[min];
      AT[min]=temp;
      
      temp=ET[i];
      ET[i]=ET[min];
      ET[min]=temp;
      
      temp=PID[i];
      PID[i]=PID[min];
      PID[min]=temp;
    }
    for(i=0;i< n;i++){
      RT[i]=ET[i];
    }
    RT[n]=9999;
    j=0;
    for(min=0;j!=n;min++){
      temp=n;
      for(i=0;i< n;i++){
        if(AT[i]<=min && RT[i]< RT[temp] && RT[i]>0){
          temp=i;
        }
      }
      RT[temp]--;
      if(RT[temp]==0){
        j++;
        thrpt=min+1;
        CT[temp]=thrpt;
        if(maxCT< thrpt)
        {
          maxCT=thrpt;
        }
      }
    }
    printf("Process\tArrival Time\tExecution Time\tCompletion Time\tTAT\tWaiting Time\n");
    for(i=0;i< n;i++){
      TAT[i]=CT[i]-AT[i];
      WT[i]=TAT[i]-ET[i];
      avg_TAT=avg_TAT+TAT[i];
      avg_WT=avg_WT+WT[i];
      printf("P%d\t%d\t\t%d\t\t%d\t\t%d\t%d\n",PID[i],AT[i],ET[i],CT[i],TAT[i],WT[i]);
    }
    avg_TAT=(double)avg_TAT/n;
    avg_WT=(double)avg_WT/n;
    thrpt=(double)n/(maxCT-AT[0]);
    printf("\nAvg.TAT=%.2f\n",avg_TAT);
    printf("Avg.WT=%.2f\n",avg_WT);
    printf("Throughput=%.2f",thrpt);
  }
  return 0;
}

Output:

Please enter number of processes
5
Enter details for process 1:
Arrival Time: 3
Execution Time: 4
Enter details for process 2:
Arrival Time: 5
Execution Time: 3
Enter details for process 3:
Arrival Time: 2
Execution Time: 8
Enter details for process 4:
Arrival Time: 7
Execution Time: 1
Enter details for process 5:
Arrival Time: 3
Execution Time: 6
Process Arrival Time    Execution Time  Completion Time TAT     Waiting Time
P3      2               8               24              22      14
P1      3               4               7               4       0
P5      3               6               17              14      8
P2      5               3               11              6       3
P4      7               1               8               1       0

Avg.TAT=9.40
Avg.WT=5.00
Throughput=0.23