priority.c

// 1. Start
// 2. Input the processes, their burst time , arrival time ,priority 
// 3. Set currentTime=arrivalTime of smallest process
// 3. Sort the processes according to priority 
// 4. Take the unvisited process with minimum burst time and check if it has arrived in ready queue
// 5. If it has arrived, find waiting time ,turnaround time,completion time and set it as visited. else move to next process
//                 a)waitingTime = currentTime – arrivalTime;
//                 b)turnAroundTime = waitingTime+ burstTime;
//                 c)completionTime= currentTime + burst[i];
//  7.If no process is  there in queue, increment current time 
//  8. Continue traversing till each process is scheduled
//  9. Find average waiting time = total_waiting_time / no_of_processes
// 10. Find average turnaround time = total_turnaround_time / no_of_processes
// 11. End


#include <stdio.h>
int n, i, j, w, yes, temp, completionTime[10], proc[10], loop, smallest, current_time, sorted[10], priority[10], arrival[10] = {0}, visited[10] = {0}, tat[10], order[10], wt[10], burst[10] = {0}, visited[10];
float total_tat = 0, total_wt = 0;
void swap(int *xp, int *yp)
{
    int temp = *xp;
    *xp = *yp;
    *yp = temp;
}
void Sort(int arr[], int n)
{
    int i, j;
    for (i = 1; i < n; i++)
        for (j = i + 1; j <= n; j++)
            if (arr[i] > arr[j])
            {
                swap(&priority[i], &priority[j]);
                swap(&burst[i], &burst[j]);
                swap(&proc[i], &proc[j]);
                swap(&arrival[i], &arrival[j]);
            }
}
int main()
{
    printf("\n-------------------------------");
    printf("\nPROGRAM : PRIORITY SCHEDULING \n\n");
    printf("---------------------------------\n");

    printf("Enter no of process : ");
    scanf("%d", &n);
    for (i = 1; i <= n; i++)
    {
        printf("\nArrival time of process %d is :", i);
         scanf("%d", &arrival[i]);
        printf("\nBurst time of process %d is :", i);
        scanf("%d", &burst[i]);
        printf("\nPriority of process %d is :", i);
        scanf("%d", &priority[i]);
        proc[i] = i;
        visited[i] = 0;
    }

    smallest = arrival[1];
    j = smallest;
    for (loop = 1; loop <= n; loop++)
    {
        if (smallest > arrival[loop])
        {
            smallest = arrival[loop];
            j = loop;
        }
    }
    current_time = smallest;
    j = 1;
    Sort(priority, n);
    while (j <= n)
    {
        yes = 0;
        for (int i = 1; i <= n; i++)
        {
            if (visited[i] == 0 && current_time >= arrival[i])
            {
                yes = 1;
                order[j] = proc[i];
                visited[i] = 1;
                wt[i] = current_time - arrival[i];
                tat[i] = wt[i] + burst[i];
                completionTime[i] = current_time + burst[i];
                total_wt += wt[i];
                total_tat += tat[i];
                current_time = completionTime[i];
                ++j;
                break;
            }
        }
        if (yes == 0)
        {
            ++current_time;
        }
    }
    total_wt = total_wt / n;
    total_tat = total_tat / n;
    printf("order in which process get executed :\t");
    for (i = 1; i <= n; i++)
    {
        printf("%d \t ", order[i]);
    }
 printf("\n                  arrival_time         Burst_time     Turn_around_time      waiting_time       completion time");
 for (i = 1; i <= n; i++) 
 {
        printf("\nprocess%d                  %d                  %d                    %d                    %d                 %d ",proc[i], arrival[i], burst[i], tat[i],wt[i],completionTime[i]);
 }
 printf("\n\n Average waiting time is %.2f", total_wt);
 printf("\n Average turn around time is %.2f", total_tat);
}