Part 2

day_3/Makefile

@@ -0,0 +1,6 @@
+obj-m = aoc2023p2.o
+all:
+	make -C /lib/modules/$(shell uname -r)/build/ M=$(PWD) modules
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
+

day_3/answer1

@@ -1 +1 @@
-507214
+Part number count: 507214

day_3/answer2

@@ -0,0 +1 @@
+Sum of ratios: 72553319

day_3/aoc2023p2.c

@@ -0,0 +1,217 @@
+#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