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
|
#include "solve.h"
/* Local functions ***********************************************************/
static bool allowed_next(Move move, DfsData *dd);
static void dfs(Cube c, Step *s, SolveOptions *opts, DfsData *dd);
static void dfs_branch(Cube c, Step *s, SolveOptions *os, DfsData *dd);
static bool dfs_check_solved(Step *s, SolveOptions *opts, DfsData *dd);
static void dfs_niss(Cube c, Step *s, SolveOptions *opts, DfsData *dd);
static bool dfs_stop(Cube c, Step *s, SolveOptions *opts, DfsData *dd);
/* Local functions ***********************************************************/
static bool
allowed_next(Move move, DfsData *dd)
{
if (!possible_next(dd->last2, dd->last1, move))
return false;
if (commute(dd->last1, move))
return dd->move_position[dd->last1] < dd->move_position[move];
return true;
}
static void
dfs(Cube c, Step *s, SolveOptions *opts, DfsData *dd)
{
if (dfs_stop(c, s, opts, dd))
return;
if (dfs_check_solved(s, opts, dd))
return;
dfs_branch(c, s, opts, dd);
if (opts->can_niss && !dd->niss)
dfs_niss(c, s, opts, dd);
}
static void
dfs_branch(Cube c, Step *s, SolveOptions *opts, DfsData *dd)
{
Move m, l1 = dd->last1, l2 = dd->last2, *moves = dd->sorted_moves;
int i, maxnsol = opts->max_solutions;
for (i = 0; moves[i] != NULLMOVE && dd->sols->len < maxnsol; i++) {
m = moves[i];
if (allowed_next(m, dd)) {
dd->last2 = dd->last1;
dd->last1 = m;
append_move(dd->current_alg, m, dd->niss);
dfs(apply_move(m, c), s, opts, dd);
dd->current_alg->len--;
dd->last2 = l2;
dd->last1 = l1;
}
}
}
static bool
dfs_check_solved(Step *s, SolveOptions *opts, DfsData *dd)
{
if (dd->lb != 0)
return false;
if (dd->current_alg->len == dd->d) {
if (s->is_valid(dd->current_alg) || opts->all)
append_alg(dd->sols, dd->current_alg);
if (opts->verbose)
print_alg(dd->current_alg, false);
}
return true;
}
static void
dfs_niss(Cube c, Step *s, SolveOptions *opts, DfsData *dd)
{
Move l1 = dd->last1, l2 = dd->last2;
CubeTarget ct;
ct.cube = apply_move(inverse_move(l1), (Cube){0});
ct.target = 1;
if (dd->current_alg->len == 0 || s->estimate(ct)) {
dd->niss = true;
dd->last1 = NULLMOVE;
dd->last2 = NULLMOVE;
dfs(inverse_cube(c), s, opts, dd);
dd->last1 = l1;
dd->last2 = l2;
dd->niss = false;
}
}
static bool
dfs_stop(Cube c, Step *s, SolveOptions *opts, DfsData *dd)
{
CubeTarget ct = {
.cube = c,
.target = dd->d - dd->current_alg->len
};
if (dd->sols->len >= opts->max_solutions)
return true;
dd->lb = s->estimate(ct);
if (opts->can_niss && !dd->niss)
dd->lb = MIN(1, dd->lb);
if (dd->current_alg->len + dd->lb > dd->d)
return true;
return false;
}
/* Public functions **********************************************************/
AlgList *
solve(Cube cube, Step *step, SolveOptions *opts)
{
AlgListNode *node;
DfsData dd;
Cube c;
prepare_step(step, &dd);
if (step->detect != NULL)
step->pre_trans = step->detect(cube);
c = apply_trans(step->pre_trans, cube);
if (step->ready != NULL && !step->ready(c)) {
fprintf(stderr, "Cube not ready for solving step: ");
fprintf(stderr, "%s\n", step->ready_msg);
return dd.sols;
}
for (dd.d = opts->min_moves;
dd.d <= opts->max_moves &&
!(dd.sols->len && opts->optimal_only) &&
dd.sols->len < opts->max_solutions;
dd.d++) {
if (opts->verbose)
fprintf(stderr,
"Found %d solutions, searching depth %d...\n",
dd.sols->len, dd.d);
dfs(c, step, opts, &dd);
}
for (node = dd.sols->first; node != NULL; node = node->next)
transform_alg(inverse_trans(step->pre_trans), node->alg);
free_alg(dd.current_alg);
return dd.sols;
}
|
