#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define N 100

typedef struct {
  int number[N];
  int choosing[N];
} lock;

void
Init(lock l)
{
  int i;
  for (i = 0; i < N; ++i)
    {
      l.choosing[i] = l.number[i] = 0;
    }
}

int
Max(int* a, int length)
{
  int i;
  int max = a[0];
  for (i = 1; i < length; ++i)
    {
      if (a[i] > max)
        max = a[i];
    }

  return max;
}

void
Lock(lock l, int id)
{
  l.choosing[id] = 1;
  l.number[id] = Max(l.number, N) + 1;
  l.choosing[id] = 0;


  int j;
  for (j = 0; j < N; j++)
    {
      if (j == id)
        continue;

      while (1)
	{
	  if (l.choosing[j] == 0)
            break;
	}
 
      while (1)
        {
          if (l.number[j] == 0)
            break;
          if ((l.number[j] > l.number[id])
	      || (l.number[j] == l.number[id] && j > id))
	    break;
        }
    }
}

void
Unlock(lock l, int id)
{
  l.number[id] = 0;
}

lock LOCK;
int counter;

void*
thread_code(void* data)
{
  int id = (long) data;


  int i;
  for (i = 0; i < 10; ++i)
    {
      Lock(LOCK, id);
      counter++;
      Unlock(LOCK, id);
    }
}


int
main(int argc, char* argv[])
{
  counter = 0;
  Init(LOCK);
  pthread_t threads[N];

  int i;
  for (i = 0; i < N; i++) {
    pthread_create(&threads[i], NULL, thread_code, (void *) i);
  }

  for (i = 0; i < N; i++) {
    pthread_join(threads[i], NULL);
  }

  printf("Counter: %d\n", counter);
  return 0;
}