aoc2023_day15.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
	int acc = 0;
	int buf = 0;
	char *data = NULL;
	char *start;
	struct {
		int len;
		struct {
			char *str;
			int weight;
		} lens[9];
	} table[256] = {0};
	size_t len = 0;
	getline(&data, &len, stdin);
	start = data;
	for (char *c = data; *c != '\n'; c++) {
		if (*c == ',') {
			acc += buf;
			buf = 0;
			start = c + 1;
			continue;
		}
		int ix = buf;
		buf = ((buf + *c) * 17) & 255;
		if (*c == '=' || *c == '-') {
			int set = *c == '=' ? c[1] - '0' : -1;
			*c = '\0';
			int shifted = 1;
			for (int i = 0; i < table[ix].len; i++) {
				if (!strcmp(table[ix].lens[i].str, start)) {
					if (~set) {
						table[ix].lens[i].weight = set;
						shifted = 0;
					} else {
						for (int j = i + 1; j < table[ix].len; j++) {
							table[ix].lens[j - 1] = table[ix].lens[j];
						}
						--table[ix].len;
					}
					break;
				}
			}
			if (shifted && ~set) {
				int new_ix = table[ix].len;
				table[ix].lens[new_ix].str = start;
				table[ix].lens[new_ix].weight = set;
				++table[ix].len;
			}
		}
	}
	printf("%d\n", acc + buf);
	int power = 0;
	for (int i = 0; i < 256; i++) {
		int cnt = 0;
		for (int j = 0; j < table[i].len; j++) {
			cnt += (j + 1) * table[i].lens[j].weight;
		}
		power += (i + 1) * cnt;
	}
	printf("%d\n", power);
	free(data);
	exit(0);
}