aoc2023/day3/p2.c

116 lines
2.8 KiB
C
Raw Normal View History

2023-12-03 18:27:32 +04:00
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#define ISDIGIT(c) (c >= 0x30 && c <= 0x39)
2023-12-03 18:31:34 +04:00
int32_t parse_number(char *line, ssize_t j);
2023-12-03 18:27:32 +04:00
int main(int argc, char **argv) {
FILE *input;
char *line = NULL;
size_t line_length = 0;
if (argc == 1 || argv[1][0] == '-')
input = stdin;
else if ((input = fopen(argv[1], "r")) == NULL) {
printf("Cannot open file %s\n", argv[1]);
return -1;
}
char **engine = NULL;
ssize_t engine_line_size = 0;
ssize_t engine_lines = 0;
while (getline(&line, &line_length, input) != -1) {
ssize_t len = strlen(line)-1;
if (engine == NULL) {
engine = (char **) calloc(len, sizeof(char*));
engine_line_size = len;
}
engine[engine_lines] = (char*) calloc(len, sizeof(char));
memcpy(engine[engine_lines], line, len);
++engine_lines;
memset(line, 0, line_length);
}
int32_t part_number = 0;
for (ssize_t i = engine_lines-1; i >= 0; --i) {
for (ssize_t j = engine_line_size-1; j >= 0; --j) {
if (engine[i][j] != '*')
continue;
int32_t n = 1;
int8_t p = 0;
if (ISDIGIT(engine[i][j+1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i], j+1);
2023-12-03 18:27:32 +04:00
p++;
}
if (ISDIGIT(engine[i][j-1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i], j-1);
2023-12-03 18:27:32 +04:00
p++;
}
if (ISDIGIT(engine[i+1][j])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i+1], j);
2023-12-03 18:27:32 +04:00
p++;
} else {
if (ISDIGIT(engine[i+1][j+1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i+1], j+1);
2023-12-03 18:27:32 +04:00
p++;
}
if (ISDIGIT(engine[i+1][j-1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i+1], j-1);
2023-12-03 18:27:32 +04:00
p++;
}
}
if (ISDIGIT(engine[i-1][j])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i-1], j);
2023-12-03 18:27:32 +04:00
p++;
} else {
if (ISDIGIT(engine[i-1][j+1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i-1], j+1);
2023-12-03 18:27:32 +04:00
p++;
}
if (ISDIGIT(engine[i-1][j-1])) {
2023-12-03 18:31:34 +04:00
n *= parse_number(engine[i-1], j-1);
2023-12-03 18:27:32 +04:00
p++;
}
}
if (p >= 2)
part_number += n;
}
}
for (ssize_t i = 0; i < engine_lines; ++i)
free(engine[i]);
free(engine);
printf("%d\n", part_number);
return 0;
}
2023-12-03 18:31:34 +04:00
int32_t parse_number(char *line, ssize_t j) {
2023-12-03 18:27:32 +04:00
int32_t n = 0;
int32_t multiplier = 1;
while (ISDIGIT(line[j+1])) j++;
2023-12-03 18:27:32 +04:00
while (ISDIGIT(line[j])) {
2023-12-03 18:31:34 +04:00
n += (line[j]&0xf) * multiplier;
2023-12-03 18:27:32 +04:00
multiplier *= 10;
j--;
}
return n;
}