First come first serve

// ALGORITHM:
// 1. Start
// 2. Input the processes, their burst time  and arrival time 
// 3. Sort the processes according to arrival time
// 4. Find  completion Time 
//   	a)for first process  , completionTime = bursttime + arrivaltime[1]
//    	b)for other processes , completionTime+=burstTime
// 5. Find turnaround time (tat) = completionTime-arrivalTime , for all processes
// 6. Find waiting time=turnaroundTime-burstTime , for all processes
// 7. if waiting time < 0 then 
//           a)completionTime += abs(waitingTime);
//           b)turnaroundtime += abs(waitingTime);
//           c)waitingTime = 0;
// 6. Find average waiting time = total_waiting_time / no_of_processes
// 7. Find average turnaround time = total_turnaround_time / no_of_processes
// 8. End

#include <stdio.h>
#include <stdlib.h>
int n, i, j, temp = 0, t, completionTime[10], tat[10], wt[10], burst[10] = {0}, arrival[10] = {0}, order[10] = {0};
float total_tat = 0, total_wt = 0;
void swap(int *xp, int *yp)
{
    int t = *xp;
    *xp = *yp;
    *yp = t;
}
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(&arrival[i],&arrival[j]);
                swap(&burst[i], &burst[j]);
                swap(&order[i], &order[j]);
            }
}
int main()
{
    printf("\n-------------------------------");
    printf("\nPROGRAM  : FIRST COME FIRST SERVE \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]);
        order[i] = i;
    }
    Sort(arrival, n);
    for (i = 1; i <= n; i++)
    {
        if (i == 1)
        {
            temp = burst[i] + arrival[1];
            completionTime[i] = temp;
            tat[i] = completionTime[i] - arrival[i];
            wt[i] = tat[i] - burst[i];
            total_tat = total_tat + tat[i];
        }
        else
        {
            temp = temp + burst[i];
            completionTime[i] = temp;
            tat[i] = completionTime[i] - arrival[i];
            wt[i] = tat[i] - burst[i];
            if (wt[i] < 0)
            {
                completionTime[i] = completionTime[i] + abs(wt[i]);
                temp = completionTime[i];
                tat[i] += abs(wt[i]);
                wt[i] = 0;
            }
            total_wt = total_wt + wt[i];
            total_tat = total_tat + tat[i];
        }
    }

    total_wt = total_wt / n;
    total_tat = total_tat / n;
    printf("\norder in which process get executed :\t");
    for (i = 1; i <= n; i++)
    {
        printf("%d \t ", order[i]);
    }
    printf("\n\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", order[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 is %.2f\n", total_tat);
}