aoc23/03/part1.c

72 lines
2.1 KiB
C

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#define LINELENGTH 150
#define NEXT(X) ((X + 3 + 1) % 3)
#define PREV(X) ((X + 3 - 1) % 3)
/* I wish I had python generator or Go coroutine... */
#define STATE_BEGIN 0
#define STATE_READING 1
#define STATE_END 2
int read_state = STATE_BEGIN;
/* Return at least 3 lines; first and last lines and first chars are all '.' */
char* readline(char* buf, int max_size) {
switch (read_state) {
case STATE_BEGIN:
memset(buf, '.', max_size);
buf[max_size - 2] = '\n';
buf[max_size - 1] = '\0';
read_state = STATE_READING;
return buf;
case STATE_READING:
buf[0] = '.';
if (!fgets(buf + 1, max_size, stdin)) {
memset(buf, '.', max_size);
buf[max_size - 2] = '\n';
buf[max_size - 1] = '\0';
read_state = STATE_END;
}
return buf;
case STATE_END:
return NULL;
}
}
#define IS_SYMBOL(X) ((X < '0' || X > '9') && X != '.' && X != '\n')
#define IS_ADJACENT_SYMBOL(buf, i, j) ( \
IS_SYMBOL(buf[i][j - 1]) || IS_SYMBOL(buf[i][j + 1]) || \
IS_SYMBOL(buf[PREV(i)][j]) || IS_SYMBOL(buf[NEXT(i)][j]) || \
IS_SYMBOL(buf[PREV(i)][j - 1]) || IS_SYMBOL(buf[PREV(i)][j + 1]) || \
IS_SYMBOL(buf[NEXT(i)][j - 1]) || IS_SYMBOL(buf[NEXT(i)][j + 1]))
int main(void) {
char buf[3][LINELENGTH];
int sum = 0;
readline(buf[0], LINELENGTH);
readline(buf[1], LINELENGTH);
for (int i = 1; readline(buf[NEXT(i)], LINELENGTH); i = NEXT(i)) {
bool is_part = false;
int num = 0;
for (int j = 1; buf[i][j]; j++) { // j = 0 is '.' guard
if (buf[i][j] >= '0' && buf[i][j] <= '9') {
num = num * 10 + (buf[i][j] - '0');
is_part = is_part || IS_ADJACENT_SYMBOL(buf, i, j);
} else {
sum += is_part ? num : 0;
is_part = false;
num = 0;
}
}
}
printf("%d\n", sum);
return 0;
}