1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
#include <ctype.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "aocdailies.h"
#include "aocutils.h"
/* === aoc202406 =======================================================
Hmmm, I've done something like this already this year... on day 4
I need rcmap() moved to aocutils ... done; now it's called `linearize2d`
===================================================================== */
void aoc202406(char *data, size_t len) {
(void)data;
|
>
>
>
>
>
>
>
>
>
>
>
>
>
<
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
|
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
|
#include <ctype.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "aocdailies.h"
#include "aocutils.h"
/* === aoc202406 =======================================================
Hmmm, I've done something like this already this year... on day 4
I need rcmap() moved to aocutils ... done; now it's called `linearize2d`
===================================================================== */
static bool validpos(unsigned s, int r, int c) {
if (r < 0) return false;
if (c < 0) return false;
if ((unsigned)r >= s - 1) return false;
if ((unsigned)c >= s - 1) return false;
return true;
}
static void rightturn(int *drow, int *dcol) {
if (*drow) { *dcol = -*drow; *drow = 0; }
else { *drow = *dcol; *dcol = 0; }
}
void aoc202406(char *data, size_t len) {
(void)len;
// assume data is well-formatted and has the same number of rows and columns
unsigned size = 1 + strchr(data, '\n') - data;
unsigned linear_pos = strchr(data, '^') - data;
int row_pos = (int)(linear_pos / size);
int col_pos = (int)(linear_pos % size);
int deltarow = -1, deltacol = 0;
//printf("character at [%u, %u] is '%c'\n", row_pos, col_pos, data[linearize2d(size, row_pos, col_pos)]);
unsigned visited = 1;
data[linearize2d(size, (unsigned)row_pos, (unsigned)col_pos)] = 'X'; // initial place visited
while (validpos(size, row_pos + deltarow, col_pos + deltacol)) {
switch (data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))]) {
default: exit(EXIT_FAILURE); // does not happen
case '#': rightturn(&deltarow, &deltacol); break;
case '.': visited++;
data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))] = 'X';
/*fallthrough*/
case 'X': row_pos += deltarow;
col_pos += deltacol;
break;
}
}
printf("The guard visits %u positions before leaving the area.\n", visited);
}
/* === aoc202405 =======================================================
===================================================================== */
static int ppcmp(unsigned a, unsigned b, unsigned (*r)[2], size_t nr) {
for (size_t k = 0; k < nr; k++) {
|