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
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
|
#include <stdint.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <stdbool.h>
typedef uint8_t byte;
typedef int8_t rang_t;
typedef struct {
byte value;
rang_t rang;
} elem_t;
typedef struct {
int len;
elem_t *elem;
} map_t;
map_t *map_g;
/* resolve {{{ */
/* returns true if the map is empty, otherwise returns false */
static bool map_is_empty(void)
{
for (int i = 0; i < map_g->len; i++) {
if (map_g->elem[i].rang == -1) {
return false;
}
}
return true;
}
/* return the index of the next element */
static inline int get_next_case(int current)
{
return (current + map_g->elem[current].value) % map_g->len;
}
/* return the index of the previous element */
static inline int get_prev_case(int current)
{
int prev = current - map_g->elem[current].value;
if (current < map_g->elem[current].value)
prev += map_g->len;
return prev;
}
static int perform_resolve_god_hands(int activated, int offset)
{
int next, prev;
/* this one is already activated, not possible captain */
if (map_g->elem[activated].rang != -1) {
return -1;
}
/* activate the current case */
map_g->elem[activated].rang = offset;
if (map_is_empty()) {
/* we won */
return 0;
}
next = get_next_case(activated);
prev = get_prev_case(activated);
if (perform_resolve_god_hands(next, offset + 1) == 0)
return 0;
if (perform_resolve_god_hands(prev, offset + 1) == 0)
return 0;
/* reset to default */
map_g->elem[activated].rang = -1;
return -1;
}
int solve_god_hands(map_t *map)
{
for (int i = 0; i < map->len; i++) {
map->elem[i].rang = -1;
}
map_g = map;
for (int i = 0; i < map->len; i++) {
if (perform_resolve_god_hands(i, 0) == 0) {
return 0;
}
}
return -1;
}
/* }}} */
static void display_solution(const map_t *map)
{
for (int i = 0; i < map->len; i++) {
/* run through the order */
for (int j = 0; j < map->len; j++) {
/* run through the elems */
assert (map->elem[j].rang != -1);
if (map->elem[j].rang == i) {
printf("[%d] ", j);
break;
}
}
}
putchar('\n');
}
int main(void)
{
map_t map;
char buffer[16];
/* get the length of the map */
for (;;) {
if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
fputs("size of the map: ", stdout);
}
if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
return 0;
}
/* TODO replace with strtol to handle errors of type 42(.*) */
map.len = atoi(buffer);
if (map.len <= 0) {
fprintf(stderr, "the map has an invalid size\n");
if (!isatty(STDIN_FILENO))
return -1;
continue;
}
break;
}
map.elem = malloc(sizeof(elem_t) * map.len);
for (int i = 0; i < map.len; i++) {
if (isatty(STDIN_FILENO) && isatty(STDOUT_FILENO))
printf("(%02d/%02d): ", i + 1, map.len);
fflush(stdout);
if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
return 0;
}
/* TODO check for errors (i.e. not numbers and negative values */
map.elem[i].value = atoi(buffer);
}
if ((solve_god_hands(&map)) != 0) {
fputs("cannot solve the paradox, kupo :-/\n", stderr);
} else {
fputs("we solved the paradox kupo! :-)\n", stdout);
display_solution(&map);
}
return 0;
}
|
