SJF Scheduling | Steve Robinson

#include <stdio.h>
#include <malloc.h>

struct process_struct
{
    int burst_time,org_bt;
    int waiting_time;
    int turnaroundtime;
};

void main()
{
    int n,i,j,total_burst_time=0,shortest_job,total_WT=0,total_TAT=0;
    float avg_WT,avg_TAT;

    printf("\nSJF Scheduling Algorithm Simulation\n");
    printf("\n\nPlease Enter the number of Processes: ");
    scanf("%d",&n);

    struct process_struct *process=(struct process_struct*)malloc(sizeof(struct process_struct)*n);

    printf("\nPlease Enter the Burst Time (BT) for the processes....\n");

    for(i=0;i<n;i++)
    {
        printf("\nProcess %d BT: ",i);
        scanf("%d",&process[i].burst_time);
        process[i].org_bt=process[i].burst_time;
        total_burst_time+=process[i].burst_time;
        process[i].waiting_time=0;
        process[i].turnaroundtime=0;
    }

    shortest_job=0;

    for(i=0;i<total_burst_time;)
    {

        for(j=0;j<n;j++)
        {
            if(process[j].burst_time<process[shortest_job].burst_time&&process[j].burst_time!=0)
                shortest_job=j;
        }

        i=i+process[shortest_job].burst_time;


        for(j=0;j<n;j++)
        {
            if(j!=shortest_job&&process[j].burst_time!=0)
                process[j].waiting_time+=process[shortest_job].burst_time;
        }

        process[shortest_job].burst_time=0;

        for(j=0;j<n;j++)
            if(process[j].burst_time!=0)
                {
                    shortest_job=j;
                    break;
                }
    }

    for(i=0;i<n;i++)
    {
            process[i].turnaroundtime=process[i].org_bt+process[i].waiting_time;
            total_WT+=process[i].waiting_time;
            total_TAT+=process[i].turnaroundtime;
    }

    avg_TAT=total_TAT/(float)n;
    avg_WT=total_WT/(float)n;

    printf("\n\nProcess ID\tBurst Time\tWaiting Time\tTurn Around Time\n---------------------------------------------------------------\n");
    for(i=0;i<n;i++)
    {
        printf("\n%d\t\t%d\t\t%d\t\t%d",i,process[i].org_bt,process[i].waiting_time,process[i].turnaroundtime);
    }
    printf("\n\nThe Average Waiting Time = %.2f",avg_WT);
    printf("\n\nThe Average Turn Around Time = %.2f",avg_TAT);

}