104 lines
2.1 KiB
C
104 lines
2.1 KiB
C
#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "aoc.h"
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typedef struct {
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char *contents;
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size_t size;
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} Backpack;
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typedef struct {
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Backpack *backpacks;
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size_t count;
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} day3_Data;
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static void *day3_parse(char **lines, int line_count)
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{
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day3_Data *data = calloc(1, sizeof(day3_Data));
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Backpack *backpacks = calloc(line_count, sizeof(Backpack));
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data->backpacks = backpacks;
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data->count = line_count;
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for (size_t i = 0; i < line_count; i++) {
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backpacks[i].size = strlen(lines[i]);
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backpacks[i].contents = lines[i];
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}
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return data;
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}
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static bool contains(char needle, char* haystack, size_t len)
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{
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for (size_t i = 0; i < len; i++) {
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if (haystack[i] == needle) {
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return true;
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}
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}
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return false;
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}
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static char find_common(char *str1, char* str2, size_t len)
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{
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for (size_t i = 0; i < len; i++) {
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if (contains(str1[i], str2, len)) {
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return str1[i];
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}
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}
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return 0;
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}
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static int get_priority(char c)
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{
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if ('a' <= c && c <= 'z') {
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return (c - 'a') + 1;
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} else if ('A' <= c && c <= 'Z') {
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return (c - 'A') + 27;
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}
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return 0;
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}
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static int day3_part1(void *p)
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{
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day3_Data *data = (day3_Data*)p;
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int result = 0;
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for (size_t i = 0; i < data->count; i++) {
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Backpack *b = &data->backpacks[i];
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char common = find_common(b->contents, b->contents+b->size/2, b->size/2);
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if (common) {
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result += get_priority(common);
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} else {
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fprintf(stderr, "Unknown common char at line: %zu\n", i+1);
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}
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}
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return result;
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}
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static int day3_part2(void *p)
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{
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day3_Data *data = (day3_Data*)p;
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int result = 0;
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for (size_t i = 0; i < data->count; i+=3) {
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Backpack *b1 = &data->backpacks[i+0];
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Backpack *b2 = &data->backpacks[i+1];
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Backpack *b3 = &data->backpacks[i+2];
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bool found = false;
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for (size_t j = 0; j < b1->size; j++) {
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char c = b1->contents[j];
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if (contains(c, b2->contents, b2->size) && contains(c, b3->contents, b3->size)) {
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result += get_priority(c);
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found = true;
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break;
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}
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}
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if (!found) {
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fprintf(stderr, "Unknown common char at line: %zu-%zu\n", i+1, i+3);
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}
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}
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return result;
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}
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ADD_SOLUTION(3, day3_parse, day3_part1, day3_part2);
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