aoc_omni/c/2022/2/rock_paper_scissors.c

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

#include "../../lib/aoc.h"

int round_score_p1(const char *round) {
  int opponent_shape = round[0] - 'A' + 1;
  int player_shape = round[2] - 'X' + 1;
  int result = (((player_shape - opponent_shape) + 4) % 3) * 3;
  return player_shape + result;
}

int round_score_p2(const char *round) {
  int opponent_shape = round[0] - 'A' + 1;
  int result = (round[2] - 'X') * 3;
  int player_shape = ((result / 3) + 2 + opponent_shape) % 3;
  if (player_shape == 0) player_shape = 3;
  return player_shape + result;
}

int main() {
  int total_score_p1 = 0;
  int total_score_p2 = 0;

  char *round;
  while ((round = aoc_read_line()) != NULL) {
    total_score_p1 += round_score_p1(round);
    total_score_p2 += round_score_p2(round);
  }

  printf("Part 1: %d\n", total_score_p1);
  printf("Part 2: %d\n", total_score_p2);

  aoc_free();
  return 0;
}