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#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)
{
/* TODO: remove the commented part, was added to moves.c
static bool initialized = false;
static bool commute[NMOVES][NMOVES], pnext[NMOVES][NMOVES][NMOVES];
if (!initialized) {
Cube c1, c2;
int i, j, k;
bool p1, p2, cij;
for (i = 0; i < NMOVES; i++) {
for (j = 0; j < NMOVES; j++) {
c1 = apply_move(i, apply_move(j, (Cube){0}));
c2 = apply_move(j, apply_move(i, (Cube){0}));
commute[i][j] = equal(c1, c2) && i && j;
for (k = 0; k < NMOVES; k++) {
p1 = j && base_move(j) == base_move(k);
p2 = i && base_move(i) == base_move(k);
cij = commute[i][j];
pnext[i][j][k] = !(p1 || (cij && p2));
}
}
}
initialized = true;
}
if (!pnext[dd->last2][dd->last1][move])
return false;
if (commute[dd->last1][move])
return dd->move_position[dd->last1] < dd->move_position[move];
return true;
*/
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->feedback)
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;
AlgList *sols = new_alglist();
Cube c;
if (step->detect != NULL)
step->pre_trans = step->detect(cube);
c = apply_trans(step->pre_trans, cube);
DfsData dd = {
.m = 0,
.niss = false,
.lb = -1,
.last1 = NULLMOVE,
.last2 = NULLMOVE,
.sols = sols,
.current_alg = new_alg("")
};
if (step->ready != NULL && !step->ready(c)) {
fprintf(stderr, "Cube not ready for solving step: ");
fprintf(stderr, "%s\n", step->ready_msg);
return sols;
}
moveset_to_list(step->moveset, dd.sorted_moves);
movelist_to_position(dd.sorted_moves, dd.move_position);
for (dd.d = opts->min_moves;
dd.d <= opts->max_moves &&
!(sols->len && opts->optimal_only) &&
sols->len < opts->max_solutions;
dd.d++) {
if (opts->feedback)
fprintf(stderr,
"Found %d solutions, searching depth %d...\n",
sols->len, dd.d);
dfs(c, step, opts, &dd);
}
for (node = sols->first; node != NULL; node = node->next)
transform_alg(inverse_trans(step->pre_trans), node->alg);
free_alg(dd.current_alg);
return sols;
}
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