Sjf preemptive...with idle time

//first all the processes are taken in the array of structure  P[]
//THEN a[] contains the burst time of all the process in order of their arival
//min function calculates the minimum value in the array a[], beteen the  index number 0 to j where j is number of process which have arived
//maximum valu of j can be equal to number of process
//if the a[i] is 0 means burst time remain is 0 and hence that procee need not be processed hence we will ignore it
// if a[i] is 0 till i to j and j is not equal to the number of process then cpu is idle all the arrived porcess have been finished and waiting for new process
// if a[i] is 0 for all the process and j=number of process then all process have been finished
// Moment burst time of the process becomes 0 at that time of interval value of cl(clock) become completition time of that process



#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
struct process
{
       int at;
       int bt;
       int rt;
       int  c;//process completiotion time
       int wt;
       int trt;
       };
     
     
       int min(int *a,int j)
       {
           int min;
        int i=0;
        int flag=0;
        int pos;
        for(i=0;i<=j;i++)
        {
        if(a[i]==0)
        continue;
        min=a[i];
        pos=i;
        flag=1;
        break;
        }
        if(flag==0 &&j!=3)
        return -2;
        else if(flag==0)
        return -1;
        else
        for(i=0;i<=j;i++)
        {
        if(a[i]==0)
        continue;
        if(a[i]<min)
        {
        min=a[i];
        pos=i;
        }
       }
       return pos;
       }
void display(struct process *p)
{ 
    int i=1;
    for(i=0;i<4;i++)
    {
        printf("Arrival time%d  ",p[i].at);
        printf("Burst Time%d  ",p[i].bt);
        printf("comlete Time%d  ",p[i].c);
        printf("waiting Time%d  ",(p[i].c-p[i].at-p[i].bt));
        printf("\n\n");
}
      
  
}   
main()
{
      struct process p[100];
      int b[100];
      int a[4];//since number of process taken are four
      puts("Enetr the process arival time and burst time");
      int i=0;
      int j=0;
      while(1)
      {
    
      scanf("%d",&(p[i].at));
      scanf("%d",&(p[i].bt));
      a[j]=p[i].bt;
      j++;
      i++;
      if(i==4)
      break;
      }
    
      //array a[] contains the burst time of the process
    
      //array p[] contains the proceess
      
      int x=0;
      int y=0;
      int m;
       j=0;
       i=0;
       int cl=0;
       int pid=2;
       while(cl<p[0].at)
       {
       printf("idle  %d---",cl);
       cl++;
       printf("%d\n",cl);
    }
      while(x!=-1)
      {
        a[x]=a[x]-1;
        cl++;
        if(a[x]==0)
        p[x].c=cl;
      
        if(cl<p[i+1].at)
    {  
        x=min(a,j);
        if(x==-2)
        {
                 while(cl<p[i+1].at)
                 {
                 printf("idle  %d---",cl);
       cl++;
       printf("%d\n",cl);
                 }
               
         }
      
    }
        if(cl==p[i+1].at)
        {j++;
        x=min(a,j);
        i++;
         }
         if(i==4)
         x=min(a,3);
  
      
}  
      
    
    
    

      printf("\n\n");
     display(p);
      getch();
      }