#include<stdio.h>
#include<pthread.h>
#include<semaphore.h>
#include<conio.h>
sem_t pn_and_quespaper;
sem_t done_Assign;
sem_t paper_and_quespaper;
sem_t pn_and_paper;
void doassignment(char *ss)
{
    printf("%s -----Is doing his Assignment:-------\n",ss);
}

void *Teachers()
{
  while(1)
  {
  sem_wait(&done_Assign);
   int rs=rand()%3;
   switch (rs) {
     case 0: printf("--------------teacher puts Pen and Paper on table:------------\n");
             sem_post(&pn_and_paper);
              break;
     case 1:printf("--------------teacher has put Paper and QuestionPaper on the table:------------\n");
             sem_post(&paper_and_quespaper);
              break;
     case 2:printf("---------------------teacher has put Pen and QuestionPaper on the Table:--------------\n");
            sem_post(&pn_and_quespaper);
             break;
   }
 }
}
void *Student_Akhil()
{
  while(1){
	sleep(rand()%3);

      sem_wait(&pn_and_paper);

        doassignment("Student Akhil(has QuestionPaper)";

        printf("Student Akhil has done Assignment:\n");
        sem_post(&done_Assign);

  }

}
void *Student_Bikash()
{
  while(1){

      sem_wait(&paper_and_quespaper);
        doassignment("Student B(has Pen)");

        sleep(rand()%3);

        printf("Student Bikash has done Assignment\n");
        sem_post(&done_Assign);

  }
}
void *Student_Chetna()
{
  while(1){
	sleep(rand()%3);
      sem_wait(&pn_and_quespaper );
        doassignment("Student Chetna(has Paper)");//Wait for student Chetna to complete his Assignment


        printf("Student Chetna has done Assignment\n");
        sem_post(&done_Assign);

  }

}
int main() {

    printf("Student Akhil has QuestionPaper\n");
      printf("Student Bikash has Pen\n");
   printf("Student Chetna has Paper\n");
      sem_init(&pn_and_paper,0,0);
   sem_init(&paper_and_quespaper,0,0);

     sem_init(&pn_and_quespaper,0,0);

      sem_init(&done_Assign,0,1);
   pthread_t t1,t2,t3,v;

   pthread_create(&t1,NULL,Student_Akhil,NULL);
    pthread_create(&t2,NULL,Student_Bikash,NULL);
     pthread_create(&t3,NULL,Student_Chetna,NULL);
   pthread_create(&v,NULL,Teachers,NULL);
    pthread_join(t1,NULL);
    pthread_join(t2,NULL);
   pthread_join(t3,NULL);
   pthread_join(v,NULL);
  return 0;
}