scheduling

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int q[100],front=-1,rear=-1;
struct process
{
    char name[20];
    int at,tt,bt,wt,ct,pr,status,left;
}p[20],temp;

struct done
{
    char name[20];
    int st,ct;
}d[20];

int n,num,idle=0;
float average_wt=0,average_tt=0;

void enqueue(int j)
{
    if(front==-1 && rear==-1)
    {
        front++;
    }
    rear++;
    q[rear] = j;
}
int dequeue()
{
    int item;
    item = q[front];
    if(front == rear)
    {
        front = -1;
        rear = -1;
    }
    else
    {
        front++;
    }
    return item;
}

void read(){
    printf("ENTER THE NUMBER OF PROCESSES : ");
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        printf("\nENTER DETAILS OF PROCESS %d",i+1);
        printf("\nPROCESS NAME : ");
        scanf(" %s",p[i].name);
        printf("ARRIVAL TIME : ");
        scanf("%d",&p[i].at);
        printf("BURST TIME : ");
        scanf("%d",&p[i].bt);
        printf("PRIORITY : ");
        scanf("%d",&p[i].pr);
        p[i].left = p[i].bt;
        p[i].status = 0;
    }
}

void sort(){
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n-i-1;j++)
        {
            if(p[j].at > p[j+1].at)
            {
                temp = p[j];
                p[j] = p[j+1];
                p[j+1] = temp;
            }
        }
    }
}

void FCFS(){
    int i,j;
    for(i=0,j=0,num=0;j<n;)
    {
        if(p[j].at<=i && p[j].status==0)
        {
            if(idle==1)
            {
                d[num].ct=i;
                num++;
                idle = 0;
            }
            strcpy(d[num].name,p[j].name);
            d[num].st = i;
            d[num].ct = i + p[j].bt;
            p[j].wt = d[num].st - p[j].at;
            p[j].tt = p[j].wt + p[j].bt;
            p[j].ct = d[num].ct;
            i = d[num].ct;
            p[j].status = 1;
            j++;
            num++;

        }
        else if(idle == 0)
        {
            strcpy(d[num].name,"Idle");
            d[num].st = i;
            i++;
            idle = 1;
        }
        else
        {
            i++;
        }
    }
}

void NP_SJF(){
    int i,j,ls,fnd,min;
    for(i=0,ls=0,num=0,idle=0;ls<n;){
        for(j=0,fnd=0;j<n;j++)
        {
            if(i>=p[j].at && p[j].status==0)
            {
                if(fnd==0){
                    min = j;
                    fnd = 1;
                }
                else if(p[min].bt>p[j].bt){
                    min = j;
                }
            }
        }
        if(idle==0 && fnd==0){
            strcpy(d[num].name,"Idle");
            d[num].st = i;
            i++;
            idle = 1;
        }
        else if(fnd==1){
            if(idle==1){
                d[num].ct = i;
                num++;
                idle = 0;
            }
            strcpy(d[num].name,p[min].name);
            p[min].status =1;
            d[num].st = i;
            d[num].ct = i + p[min].bt;
            i = d[num].ct;
            p[min].ct = d[num].ct;
            p[min].tt = p[min].ct - p[min].at;
            p[min].wt = p[min].tt - p[min].bt;
            num++;
            ls++;
        }
        else{
            i++;
        }
    }
}

void NP_Priority(){
    int i,j,ls,fnd,min;
    for(i=0,ls=0,num=0,idle=0;ls<n;)
    {
        for(j=0,fnd=0;j<n;j++)
        {
            if(i>=p[j].at && p[j].status==0)
            {
                if(fnd==0)
                {
                    min = j;
                    fnd = 1;
                }
                else if((p[min].pr>p[j].pr)||(p[min].pr==p[j].pr && p[min].at>p[j].at))
                {
                    min = j;
                }
            }
        }
        if(idle==0 && fnd==0)
        {
            strcpy(d[num].name,"Idle");
            d[num].st = i;
            i++;
            idle = 1;
        }
        else if(fnd==1)
        {
            if(idle==1)
            {
                d[num].ct = i;
                num++;
                idle = 0;
            }
            strcpy(d[num].name,p[min].name);
            p[min].status =1;
            d[num].st = i;
            d[num].ct = i + p[min].bt;
            i = d[num].ct;
            p[min].ct = d[num].ct;
            p[min].tt = p[min].ct - p[min].at;
            p[min].wt = p[min].tt - p[min].bt;
            num++;
            ls++;
        }
        else
        {
            i++;
        }
    }
}

void round_robin(){
    int i,j,k,ls,t;
    printf("\nENTER THE TIME QUANTUM : ");
    scanf("%d",&t);

    for(i=0,num=0,ls=0;ls<n;)
    {
        for(j=0;j<n;j++)
        {
          if(p[j].status==0 && p[j].at<=i)
          {
            enqueue(j);
            p[j].status = 1;
          }
        }
        if(idle==0 && front == -1)
        {
          strcpy(d[num].name,"Idle");
          d[num].st = i;
          idle = 1;
          i++;
        }
        else if(front!=-1)
        {
          if(idle==1)
          {
            d[num].ct = i;
            idle = 0;
            num++;
          }
          k = dequeue();
          d[num].st = i;
          strcpy(d[num].name,p[k].name);
          if(p[k].left<=t)
          {
            d[num].ct = i+p[k].left;
            p[k].ct = d[num].ct;
            i = d[num].ct;
            p[k].tt = i - p[k].at;
            p[k].wt = p[k].tt - p[k].bt;
            p[k].status = 2;
            ls++;
            num++;
          }
          else if(p[k].left>t)
          {
            d[num].ct = i+t;
            i = d[num].ct;
            p[k].left = p[k].left-t;
            num++;
            for(j=0;j<n;j++)
            {
              if(p[j].status==0 && p[j].at<=i)
              {
                enqueue(j);
                p[j].status = 1;
              }
            }
            enqueue(k);
          }
        }
        else
        {
          i++;
        }
    }
}

void print(){
    printf("\n==============================================================================================================");
    printf("\n| NAME\t\t| ARRIVAL\t| BURST\t\t| Priority\t| COMPLETION\t| WAITING\t| TURNAROUND |\n");
    printf("--------------------------------------------------------------------------------------------------------------\n");
    for(int i=0;i<n;i++)
    {
        printf("|  %-4s\t\t| %-7d\t| %-5d\t\t| %-8d\t| %-10d\t| %-7d\t| %-10d |\n",p[i].name,p[i].at,p[i].bt,p[i].pr,p[i].ct,p[i].wt,p[i].tt);
        average_wt+=p[i].wt;
        average_tt+=p[i].tt;
    }
    printf("==============================================================================================================\n");
    printf("\n\nGANTT CHART ");
    printf("\n\t--------------------------------------------------------------------------\n\t");
    for(int i=0;i<num;i++)
    {
        printf("|");
        printf("%s\t",d[i].name);
    }
    printf(" |");
    printf("\n\t--------------------------------------------------------------------------\n\t");
    for(int i=0;i<num;i++)
    {
        printf("%d\t",d[i].st);
    }
    printf("%d\t",d[num-1].ct);
    printf("\n\nAVERAGE WAITING TIME : %f",(average_wt/n));
    printf("\nAVERAGE TURNAROUND TIME : %f\n",(average_tt/n));
}
int main()
{
    int arg1,arg2;

    while(1){
        printf("Enter your choice:\n");
        printf("1. Non-Preemptive\n2. Preemptive\n0.Exit\n");
        scanf("%d",&arg1);
        switch(arg1){
            case 1:
            {
                printf("Enter your choice:\n");
                printf("1. FCFS\n2. SJF\n3. Priority\n");
                scanf("%d",&arg2);
                switch(arg2){
                    case 1://FCFS
                    {
                        read();
                        sort();
                        FCFS();
                        print();
                        break;
                    }
                    case 2://SJF
                    {
                        read();
                        NP_SJF();
                        print();
                        break;
                    }
                    case 3://Priority
                    {
                        read();
                        NP_Priority();
                        print();
                        break;
                    }
                }
                break;
            }
            case 2: {
                printf("Enter your choice:\n");
                printf("1. Round-Robin\n");
                scanf("%d", &arg2);
                switch (arg2) {
                    case 1: //Round-Robin
                    {
                        read();
                        round_robin();
                        print();
                        break;
                    }
                }
                break;
            }
            case 0:
                exit(0);
        }
    }
}