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
|
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
|
+
-
-
+
+
+
+
+
+
-
+
-
-
-
+
-
-
-
-
-
-
-
-
-
-
+
+
+
+
-
+
-
+
+
+
+
+
+
+
+
+
+
|
#include <ctype.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "aocdailies.h"
#include "aocutils.h"
/* === aoc202407 =======================================================
Part one looks easy
Part two also easy
===================================================================== */
static unsigned long long concat(unsigned long long a, unsigned long long b) {
unsigned long long r = a, t = b;
while (b) {
r *= 10;
b /= 10;
}
return r + t;
}
static bool canbetrue(unsigned long long v, unsigned long long *a, size_t n) {
if (n == 1) return (v == *a);
static int operatorsrequired(unsigned long long v, unsigned long long *a, size_t n, int minop) {
// assumes no unsigned long long overflowing
if (n == 1) {
if (v == *a) return minop;
return 0;
}
unsigned long long tmp = a[1];
a[1] = a[0] + tmp;
if (canbetrue(v, a+1, n-1)) { a[1] = tmp; return true; }
int p = operatorsrequired(v, a+1, n-1, (minop > 2)?3:2);
a[1] = a[0] * tmp;
if (canbetrue(v, a+1, n-1)) { a[1] = tmp; return true; }
return false;
if (p) return p;
}
static bool canbetrue3(unsigned long long v, unsigned long long *a, size_t n) {
// still, let's assume no unsigned long long overflowing
if (n == 1) return (v == *a);
unsigned long long tmp = a[1];
a[1] = a[0] + tmp;
if (canbetrue3(v, a+1, n-1)) { a[1] = tmp; return true; }
a[1] = a[0] * tmp;
if (canbetrue3(v, a+1, n-1)) { a[1] = tmp; return true; }
if (canbetrue3(v, a+1, n-1)) { a[1] = tmp; return true; }
p = operatorsrequired(v, a+1, n-1, 3);
a[1] = tmp;
return false;
return p;
}
void aoc202407(char *data, size_t len) {
(void)len; // unused argument
unsigned long long calibrationtotal = 0, calibration3total = 0;
char *line = strtok(data, "\n");
unsigned long long number[50], nnumber;
while (line) {
char *err;
unsigned long long testvalue = strtoull(line, &err, 10);
err += 1; // skip ':'
nnumber = 0;
while (*err == ' ') {
number[nnumber++] = strtoul(err, &err, 10);
}
switch (operatorsrequired(testvalue, number, nnumber, 0)) {
default: break;
case 2: calibrationtotal += testvalue;
__attribute__((fallthrough));
case 3: calibration3total += testvalue;
break;
}
#if 0
if (canbetrue(testvalue, number, nnumber)) {
calibrationtotal += testvalue;
}
if (canbetrue3(testvalue, number, nnumber)) {
calibration3total += testvalue;
}
#endif
line = strtok(NULL, "\n");
}
printf("The calibration total is {%llu}.\n", calibrationtotal);
printf("The calibration total with three operators is {%llu}.\n", calibration3total);
}
/* === aoc202406 =======================================================
|
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
-
+
|
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*/
__attribute__((fallthrough));
case 'X': row_pos += deltarow;
col_pos += deltacol;
break;
}
}
printf("The guard visits %u positions before leaving the area.\n", visited);
// Part Two
|
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
-
+
|
switch (data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))]) {
default: puts("stepped on default"); exit(EXIT_FAILURE);
case '#': if (data[linearize2d(size, (unsigned)(row_pos), (unsigned)(col_pos))] == '4') looping = true;
rightturn(&deltarow, &deltacol);
break;
case '4': looping = true; break;
case '.': data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))] = '0';
/*fallthrough*/
__attribute__((fallthrough));
case '1':
case '2':
case '3': data[linearize2d(size, (unsigned)(row_pos+deltarow), (unsigned)(col_pos+deltacol))]++;
row_pos += deltarow;
col_pos += deltacol;
break;
}
|