aoc4.c

#include "aoc4.h"
#include "../common.h"
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>

CardNode *parse_cards(Node *head) {
    CardNode *cards = malloc(sizeof(CardNode));
    CardNode *tail = cards;
    char is_winner[100];
    do {
        char *value = head->value;
        memset(is_winner, 0, sizeof(is_winner));
        Common_strip_string(&value, "Card XXX: ");
        for (int i = 0; i < WINNING_AMOUNT; i++) {
            is_winner[Common_get_number_lstrip(&value)]++;
        }
        Common_strip_string(&value, " | ");
        int winners = 0;
        for (int i = 0; i < NUMBERS_AMOUNT; i++) {
            winners += is_winner[Common_get_number_lstrip(&value)];
        }
        CardNode *new = malloc(sizeof(CardNode));
        new->winners = winners;
        tail->next = new;
        tail = new;
    } while (head = head->next);
    return cards->next;
}

int sum_winners(CardNode *cards) {
    int sum = 0;
    do {
        sum += pow(2, cards->winners-1);
    } while (cards = cards->next);
    return sum;
}

int sum_copy_winners(CardNode *cards) {
    int sum = 0;
    int cw = WINNING_AMOUNT+1;
    int copies[cw];
    memset(copies, 0, sizeof(copies));
    int start = 0;
    do {
        int card_copies = copies[start%cw] + 1;
        for (int i = 0; i < cards->winners; i++) {
            copies[(start+i+1)%cw] += card_copies;
        }
        sum += card_copies;
        copies[start%cw] = 0;
        start++;
    } while (cards = cards->next);
    return sum;
}

void Day4_solve() {
    Node *head = Common_readFile("AoC4/day4.txt");
    CardNode *cards = parse_cards(head);
    int sum = sum_winners(cards);
    int sum_copy = sum_copy_winners(cards);
    printf("Answer 1st: %i\n", sum);
    printf("Answer 2nd: %i\n", sum_copy);
}