-
Notifications
You must be signed in to change notification settings - Fork 0
/
day01.c
91 lines (78 loc) · 1.85 KB
/
day01.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
const char *DIGITS[] = {"one", "two", "three", "four", "five", "six", "seven", "eight", "nine"};
int scan_part1_digit(const char *s, int length) {
if (length > 0) {
char c = *s;
if (c >= '0' && c <= '9') {
return c - '0';
}
}
return -1;
}
bool is_part2_digit(const char *s, int length, int n) {
const char *digit = DIGITS[n - 1];
int digit_length = strlen(digit);
if (digit_length <= length) {
for (int i = 0; i < digit_length; i++) {
if (s[i] != digit[i]) {
return false;
}
}
return true;
}
return false;
}
int scan_part2_digit(const char *s, int length) {
int n = scan_part1_digit(s, length);
if (n > 0) {
return n;
}
for (n = 1; n <= sizeof(DIGITS) / sizeof(const char *); n++) {
if (is_part2_digit(s, length, n)) {
return n;
}
}
return -1;
}
int find_number(const char *line, int length, int (*scan_digit)(const char *, int)) {
int first = -1;
int last = -1;
for (int i = 0; i < length; i++) {
char n = scan_digit(line + i, length - i);
if (n > 0) {
last = n;
if (first < 0) {
first = last;
}
}
}
return first * 10 + last;
}
int main(int argc, char *argv[]) {
if (argc < 2) {
fprintf(stderr, "Usage: %s <input>\n", argv[0]);
return 1;
}
FILE *file = fopen(argv[1], "r");
if (file == NULL) {
fprintf(stderr, "Could not open input!\n");
return 1;
}
char *line = NULL;
size_t length = 0;
size_t size = 0;
int part1 = 0;
int part2 = 0;
while ((length = getline(&line, &size, file)) != -1) {
if (length > 0) {
part1 += find_number(line, length, scan_part1_digit);
part2 += find_number(line, length, scan_part2_digit);
}
}
fclose(file);
printf("Part 1: %d\n", part1);
printf("Part 2: %d\n", part2);
return 0;
}