program of SJF(Shortest job first ) Scheduling algorithm (Non -preemptive).c

#include<stdio.h>
struct process
{
    int id,WT,AT,BT,TAT;
};
struct process a[10];

// function for swapping
void swap(int *b,int *c)
{
    int tem;
    tem=*c;
    *c=*b;
    *b=tem;
}

//Driver function
int main()
{
    int n,check_ar=0;
    int Cmp_time=0;
    float Total_WT=0,Total_TAT=0,Avg_WT,Avg_TAT;
    printf("Enter the number of process \n");
    scanf("%d",&n);
    printf("Enter the Arrival time and Burst time of the process\n");
    printf("AT BT\n");
    for(int i=0;i<n;i++)
    {
        scanf("%d%d",&a[i].AT,&a[i].BT);
        a[i].id=i+1;
        // here we are checking that arrival time 
        // of the process are same or different
        if(i==0)
         check_ar=a[i].AT;
         
        if(check_ar!=a[i].AT )
         check_ar=1;
        
    }
    // if process are arrived at the different time 
    // then sort the process on the basis of AT
    if(check_ar!=0)
    {
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<n-i-1;j++)
            {
                if(a[j].AT>a[j+1].AT)
                {
                      swap(&a[j].id,&a[j+1].id);
                      swap(&a[j].AT,&a[j+1].AT);
                      swap(&a[j].BT,&a[j+1].BT);
                }
            }
        }
    }
    
    // logic of SJF non preemptive algo
    // if all the process are arrived at different time
    if(check_ar!=0)
    {
        a[0].WT=a[0].AT;
        a[0].TAT=a[0].BT-a[0].AT;
        Cmp_time=a[0].TAT;
        Total_WT=Total_WT+a[0].WT;
        Total_TAT=Total_TAT+a[0].TAT;
        for(int i=1;i<n;i++)
        {
            int min=a[i].BT;
            for(int j=i+1;j<n;j++)
            {
                if(min>a[j].BT && a[j].AT<=Cmp_time)
                {
                      min=a[j].BT;
                      swap(&a[i].id,&a[j].id);
                      swap(&a[i].AT,&a[j].AT);
                      swap(&a[i].BT,&a[j].BT);
                }
                
            }
            a[i].WT=Cmp_time-a[i].AT;
            Total_WT=Total_WT+a[i].WT;
            // completion time of the process
            Cmp_time=Cmp_time+a[i].BT;
            
            // Turn Around Time of the process
            // compl-Arival
            a[i].TAT=Cmp_time-a[i].AT;
            Total_TAT=Total_TAT+a[i].TAT;
            
        }
    }
    
    // if all the process are arrived at same time
    else
    {
        for(int i=0;i<n;i++)
        {
            int min=a[i].BT;
            for(int j=i+1;j<n;j++)
            {
                if(min>a[j].BT && a[j].AT<=Cmp_time)
                {
                      min=a[j].BT;
                      swap(&a[i].id,&a[j].id);
                      swap(&a[i].AT,&a[j].AT);
                      swap(&a[i].BT,&a[j].BT);
                }
                
            }
            a[i].WT=Cmp_time-a[i].AT;
            
             // completion time of the process
            Cmp_time=Cmp_time+a[i].BT;
            
            // Turn Around Time of the process
            // compl-Arrival
            a[i].TAT=Cmp_time-a[i].AT;
            Total_WT=Total_WT+a[i].WT;
            Total_TAT=Total_TAT+a[i].TAT;
            
        }
        
    }
    
    Avg_WT=Total_WT/n;
    Avg_TAT=Total_TAT/n;

    // Printing of the results
    printf("The process are\n");
    printf("ID WT TAT\n");
    for(int i=0;i<n;i++)
    {
        printf("%d\t%d\t%d\n",a[i].id,a[i].WT,a[i].TAT);
    }
    
    printf("Avg waiting time is:- %f\n",Avg_WT);
    printf("Avg turn around time is:- %f",Avg_TAT);
    return 0;
}