# Priority Scheduling Algorithm

``````#include<stdio.h>
struct process
{
int id,WT,AT,BT,TAT,PR;
};
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 , Burst time and priority of the process\n");
printf("AT BT PR\n");
for(int i=0;i<n;i++)
{
scanf("%d%d%d",&a[i].AT,&a[i].BT,&a[i].PR);
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);
swap(&a[j].PR,&a[j+1].PR);
}
}
}
}

// logic of Priority scheduling ( 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 for completion time
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].PR;
for(int j=i+1;j<n;j++)
{
if(min>a[j].PR && a[j].AT<=Cmp_time)
{
min=a[j].PR;
swap(&a[i].id,&a[j].id);
swap(&a[i].AT,&a[j].AT);
swap(&a[i].BT,&a[j].BT);
swap(&a[i].PR,&a[j].PR);

}

}
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].PR;
for(int j=i+1;j<n;j++)
{
if(min>a[j].PR && a[j].AT<=Cmp_time)
{
min=a[j].PR;
swap(&a[i].id,&a[j].id);
swap(&a[i].AT,&a[j].AT);
swap(&a[i].BT,&a[j].BT);
swap(&a[i].PR,&a[j].PR);
}

}
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;
}
``````

This site uses Akismet to reduce spam. Learn how your comment data is processed.