thomas_2023/day_3/aoc2023p2.c

#define BREAK_MY_SHIT

#ifdef BREAK_MY_SHIT
#include <linux/module.h>     /* Needed by all modules */
#include <linux/kernel.h>     /* Needed for KERN_INFO */
#include <linux/init.h>       /* Needed for the macros */
#include <linux/ctype.h>

MODULE_LICENSE("Proprietary and Confidential; All Rights Reserved");
MODULE_AUTHOR("Urmomlel");
MODULE_DESCRIPTION("Vanguard Anticheat");
MODULE_VERSION("-6.9");
#else
#include <stdio.h>
#include <ctype.h>

#define __init
#define __exit
#define KERN_INFO
#define printk printf
#endif

#define printd printk

#include "input.h"
// #include "hint.h"

// Return index of first gear found
int find_gear(const char *line) {
    int i = 0;
    for(; *line; ++line) {
        if(*line == '*')
            return i;
        i++;
    }

    return -1;
}

// Convert string to int, return digits consumed
int get_int(const char *line, int *num_out) {
    int i = 0;
    *num_out = 0;

    // Handle the edge case that will never happen (tm)
    if(!isdigit(*line))
        return -1;

    for(; *line; ++line,++i) {
        if(!isdigit(*line))
            break;

        *num_out *= 10;
        *num_out += *line - 0x30;
    }

    return i;
}

int find_number_start(const char *line, int start) {
    printd("find_number_start\n");
    for(; start >= 0; start--) {
        printd("%c", line[start]);
        if(!isdigit(line[start]))
            return start + 1;
    }

    printd("start %d\n", start);

    // Fucking edge cases
    if(start == -1)
        return 0;

    return -1;
}

// Check for a digit, now with bounds checks
int has_digit(int y, int x) {
    if(x < 0 || x >= input_width) return 0;
    if(y < 0 || y >= input_height) return 0;

    return isdigit(input[y][x]);
}

// Search around a gear for numbers
// xxxxx
// xxxgx  <-- y
// xxxxx
// x is searched area
// g is where the "gear" is
// Return 1 if found
int search_numbers(int y, int x) {
    // *Technically* 6 are possible
    int numbers[6] = {0};
    int num_results = 0;

    // Define some vars for my sanity
    int top = y - 1;
    int bot = y + 1;
    int left = x - 1;
    int right = x + 1;

    // Check direct top and bottom to avoid further checks on those rows
    int top_has = has_digit(top, x);
    int bot_has = has_digit(bot, x);

    if(top_has) {
        printd("top %d\n", x);
        int real_start = find_number_start(input[top], x);
        get_int(&input[top][real_start], &numbers[num_results++]);
    } else {
        if(has_digit(top, left)) {
            printd("top left %d\n", left);
            int real_start = find_number_start(input[top], left);
            printd("top real %d\n", real_start);
            printd("top real %s\n", &input[top][real_start]);
            get_int(&input[top][real_start], &numbers[num_results++]);
        }
        if(has_digit(top, right)) {
            printd("top right %d\n", right);
            int real_start = find_number_start(input[top], right);
            get_int(&input[top][real_start], &numbers[num_results++]);
        }
    }

    if(bot_has) {
        int real_start = find_number_start(input[bot], x);
        printd("bot %d\n", x);
        printd("bot real %d\n", real_start);
        printd("bot real %s\n", &input[bot][real_start]);
        get_int(&input[bot][real_start], &numbers[num_results++]);
    } else {
        if(has_digit(bot, left)) {
            printd("bot left %d\n", left);
            int real_start = find_number_start(input[bot], left);
            get_int(&input[bot][real_start], &numbers[num_results++]);
        }
        if(has_digit(bot, right)) {
            printd("bot right %d\n", right);
            int real_start = find_number_start(input[bot], right);
            get_int(&input[bot][real_start], &numbers[num_results++]);
        }
    }

    // Check sides
    if(has_digit(y, left)) {
        int real_start = find_number_start(input[y], left);
        get_int(&input[y][real_start], &numbers[num_results++]);
    }
    if(has_digit(y, right)) {
        get_int(&input[y][right], &numbers[num_results++]);
    }

    printd("Found %d numbers\n", num_results);
    for(int i = 0; i < num_results; i++) {
        printd("%d: %d\n", i, numbers[i]);
    }

    if(num_results == 2)
        return numbers[0] * numbers[1];

    return 0;
}

static int __init aoc_start(void) {
    printk(KERN_INFO "aoc_start\n");

    int ratio_sum = 0;

    for(int y = 0; y < input_height; y++) {
        const char *line = input[y];
        int head = 0;
        while(1) {
            // Find a number
            int skipped = find_gear(&line[head]);
            if(skipped == -1) break;
            head += skipped;
            // Save hear index so we can pass it to search later
            int gear = head;
            // Skip past gear
            head++;

            printk("asdlkasjdlkasd %d\n", y);
            printd("context:\n");
            if(y-1 >= 0)
                printd("%s\n", input[y-1]);
            printd("%s\n", input[y]);
            if(y+1 < input_height)
                printd("%s\n", input[y+1]);
            int ratio = search_numbers(y, gear);
            printk("ratio %d\n", ratio);

            if(ratio > 0)
                ratio_sum += ratio;
        }

        printk("\n");
    }

    printk("Sum of ratios: %d\n", ratio_sum);

    return 0;
}

static void __exit aoc_end(void) {
    printk(KERN_INFO "aoc_end\n");
}

#ifdef BREAK_MY_SHIT
module_init(aoc_start);
module_exit(aoc_end);
#else
int main() {
    aoc_start();
    aoc_end();
}
#endif