AdventOfCode C 2024 day 11

#include <stdio.h>
#include <stdbool.h>
#include <math.h>
#define SIZE 100000
typedef long int num;


typedef struct {
    num number;
    int blinks_rem;
    num total_stones;
} state_t;




/**
 * @brief  check how many digits num has
 * @note   Assumes positive number
 * @param  number: The number to check
 * @retval Number of digits
 */
int get_digits(num number) {
    int count = floor(log10l(number)) + 1;
    return count;
}

num get_res(num number, int blinks, state_t *saved, int *size) {
    for (size_t i = 0; i < *size; i++) {
        if ((saved + i)->number == number && (saved + i)->blinks_rem == blinks) {
            return (saved + i)->total_stones;
        }
    }
    return -1;
}
/**
 * @brief Save the state in the cache
 * @note    Assumes this state is not saved yet. Does not save if cache is full
 */
void add_res(num number, int blinks, num res, state_t *saved, int *size) {
    if (*size >= SIZE) {
        // Prevent cache overflow.
        return;
    }
    state_t state = { number, blinks, res };
    *(saved + *size) = state;
    (*size)++;
}

num count_stones_saved(num number, int blinks, state_t *saved, int *size, int *hit, int *miss) {
    num res = get_res(number, blinks, saved, size);
    if (res != -1) {
        (*hit)++;
        return res;
    }
    (*miss)++;
    if (blinks == 0) {
        add_res(number, blinks, 1, saved, size);
        return 1;
    }
    if (number < 0) {
        printf("Overflow error occured: %ld\n", number);
    }
    if (number == 0) {
        res = count_stones_saved(1, blinks - 1, saved, size, hit, miss);
        add_res(number, blinks, res, saved, size);
        return res;
    }
    int digits = get_digits(number);
    if (digits % 2) {
        // Odd number of digits
        res = count_stones_saved(number * 2024, blinks - 1, saved, size, hit, miss);
        add_res(number, blinks, res, saved, size);
        return res;
    }
    int half = digits / 2;
    // Ex the number is 12.
    // then half = 1
    // mod = 10^1 = 10
    // 12 / 10 = 1
    // 12 % 10  = 2
    int mod = pow(10, half);
    int num1 = number % mod;
    int num2 = number / mod;
    res = count_stones_saved(num1, blinks - 1, saved, size, hit, miss) + count_stones_saved(num2, blinks - 1, saved, size, hit, miss);
    add_res(number, blinks, res, saved, size);
    return res;
}

num do_blinks(num *stones, int size, int blinks) {
    num total = 0;
    state_t states[SIZE] = { 0 };
    int state_size = 0;
    int cache_miss = 0;
    int cache_hit = 0;
    int old_miss = 0;
    int old_hit = 0;
    for (size_t i = 0; i < size; i++) {
        printf("Testing %ld: ", *(stones + i));
        num res = count_stones_saved(*(stones + i), blinks, states, &state_size, &cache_hit, &cache_miss);
        total += res;
        printf("%d sub cache hits. %d sub cache misses.\n", cache_hit - old_hit, cache_miss - old_miss);
        old_hit = cache_hit;
        old_miss = cache_miss;
    }
    printf("%d cache hits. %d cache misses.\n", cache_hit, cache_miss);
    return total;
}

int main() {
    num test[2] = { 125, 17 };
    num stones[8] = { 5, 127, 680267, 39260, 0, 26, 3553, 5851995 };
    num test2[5] = { 0, 1, 10, 99, 999 };
    printf("Part one test: %ld\n\n", do_blinks(test, 2, 25));
    printf("Part two test: %ld\n\n", do_blinks(test, 2, 75));
    printf("Part one: %ld\n\n", do_blinks(stones, 8, 25));
    printf("Part two: %ld\n\n", do_blinks(stones, 8, 75));
}