03_aliquote.c

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define MIN_RAND_NUMBER 10
#define MAX_RAND_NUMBER 60

#define STATE_YOU 0
#define STATE_BOT 1

unsigned int get_random_number() {
  time_t now;
  time(&now);
  srand(now);

  return rand() % MAX_RAND_NUMBER + MIN_RAND_NUMBER;
}

bool is_divisor(unsigned int number, unsigned int input) {
  return number % input == 0 ? true : false;  
}

unsigned int request_divisor_from_bot(unsigned int cur_number) {

  for(unsigned int i = rand() % cur_number; i > 0; i--) {
    if (is_divisor(cur_number, i) == true) {
      printf("BOT: %2d\n", i);
      return i;
    }
  }

  printf("BOT: %2d\n", 1);
  return 1;
}

unsigned int request_divisor_from_user(unsigned int cur_number) {
  unsigned int input_number;
  
  while(1) {
    printf("YOU: ");
    
    if (scanf("%u", &input_number) != 1) {
      printf("**Fehler** Eingabe keine positive, ganze Zahl\n");
      continue;
    }

    if (input_number >= cur_number) {
      printf("**Fehler** Zahl zu gross\n");
      continue;
    }

    if (is_divisor(cur_number, input_number) == false) {
      printf("**Fehler** Zahl %d ist kein Divisor von %d\n", 
             input_number, cur_number);
      continue;
    }

    return input_number;
  }
  return 0; // never reached
}

int main(int argc, char *argv[]) {
  unsigned char player_state = STATE_YOU;
  unsigned int cur_number = get_random_number();

  while(cur_number > 1) {
    printf("Number: %2d\n", cur_number);
    
    if (player_state == STATE_YOU) {
      cur_number -= request_divisor_from_user(cur_number);
    } 
    else {
      cur_number -= request_divisor_from_bot(cur_number);
    }

    player_state ^= STATE_BOT;
  }

  if (player_state == STATE_YOU) {
    printf("Du hast verloren!\n");
  }
  else {
    printf("Du hast den Bot geschlagen!\n");
  }

  return 0;
}