#include <stdio.h>
#include <stdlib.h>
#include <sys/random.h>


int ask_user(void)
{
	unsigned int rn;

	rn = 0;
	if (getrandom(&rn, sizeof(unsigned int), GRND_NONBLOCK) == 1){
		perror("getrandom");
		exit(1);
	}
	rn = rn % 3 + 1;
	printf("rn = %d\n", rn);
	return(rn);
}


void set_prize_door(int *door)
{
	printf("Select door where prize is ");
	if ((*door = ask_user()) == 0)
		exit(1);
}

void contestant_picks_door(int *door)
{
	printf("Select door for contestant ");
	if ((*door = ask_user()) == 0)
		exit(1);
}


int main(void)
{
	int prize_door;
	int door_before_switch;
	int win_switch = 0;
	int win_noswitch = 0;
	int number_games = 0;

	for(number_games = 0; number_games < 10000; number_games++){
		set_prize_door(&prize_door);
		contestant_picks_door(&door_before_switch);
		if (door_before_switch == prize_door){
			/* for not switching */
			win_noswitch++;
		}
		else{
			/* for switching */
			win_switch++;
		}
	}
	printf("Won %d (%f%%)games where we switched\n",
		win_switch, (double) win_switch / (double) number_games);
	printf("Won %d (%f%%)games where we did not switch\n",
		win_noswitch, (double) win_noswitch / (double) number_games);




	return(0);
}