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#include <queue>
// #include <priority_queue>
#include <iostream>
#include <algorithm>
#include "solver.hpp"
Solver::Solver(uint32_t pruning_tab_depth) {
pruning_table = kh_init_cube();
visited_states = kh_init_cube();
generate_pruning_table(pruning_tab_depth);
}
Solver::~Solver() {
kh_destroy_cube(pruning_table);
kh_destroy_cube(visited_states);
}
void Solver::generate_pruning_table(uint32_t depth) {
std::cerr << "Generating pruning table...\n";
cube_t initial, cube, rotated;
rot_cnt_t rot_cnt;
uint16_t rot, cnt;
int ret;
khint_t k;
std::queue<cube_t> q;
init_cube(&initial);
k = kh_put_cube(pruning_table, initial, &ret);
kh_val(pruning_table, k) = build_rot_cnt(NULL_ROT, 0);
q.push(initial);
while(!q.empty()) {
cube = q.front();
q.pop();
k = kh_get_cube(pruning_table, cube);
rot_cnt = kh_val(pruning_table, k);
cnt = get_cnt(rot_cnt);
if (cnt >= depth)
continue;
for (rot = ROT_R; rot != NULL_ROT; rot++) {
rotated = cube;
perform_rotation(&rotated, (rotations)rot);
k = kh_get_cube(pruning_table, rotated);
if (k == kh_end(pruning_table)) {
k = kh_put_cube(pruning_table, rotated, &ret);
kh_val(pruning_table, k) = build_rot_cnt(rot, cnt+1);
q.push(rotated);
}
}
}
std::cerr << "Generated\n";
}
std::vector<rotations> Solver::get_solve_pruning(cube_t cube) {
khiter_t k;
cube_t initial;
rotations rot, rev_rot;
std::vector<rotations> result(0);
init_cube(&initial);
k = kh_get_cube(pruning_table, cube);
if (k == kh_end(pruning_table)) {
return result;
}
while (!kh_cube_hash_equal(cube, initial)) {
rot = get_rot(kh_val(pruning_table, k));
rev_rot = reverse_rotation(rot);
result.push_back(rev_rot);
perform_rotation(&cube, rev_rot);
k = kh_get_cube(pruning_table, cube);
}
return result;
}
#define TILE_VAL(i) (face>>((i)<<2)&0xf)
#define CMP_TILES(i, j) (uint32_t)(!!(TILE_VAL(i)==TILE_VAL(j)))
/* Count number of neibourgh tiles of the same color */
__attribute__((optimize("unroll-loops")))
heur_t Solver::heuristic(const cube_t cube, const uint16_t moves_cnt) {
heur_t value = 0;
int i, j;
face_t face;
for (i = 0; i < 6; i++) {
face = cube.faces[i];
for (j = 0; j < 7; j++)
value += CMP_TILES(j,j+1);
value += CMP_TILES(7,0);
for (j = 0; j < 4; j++)
value += (TILE_VAL((j<<1)+1)==i);
}
/* This is absolutely random */
return value * 2 - moves_cnt * 3;
}
typedef std::pair<cube_t, heur_t> qentry_t;
class Comp {
public:
bool operator()(const qentry_t &e1, const qentry_t &e2) {
return e1.second < e2.second;
}
};
std::vector<rotations> Solver::retrieve_solution(cube_t cube) {
std::vector<rotations> result;
rot_cnt_t rot_cnt;
rotations rot, rev_rot;
khiter_t k;
k = kh_get_cube(visited_states, cube);
assert(k != kh_end(visited_states));
rot_cnt = kh_val(visited_states, k);
while ((rot = get_rot(rot_cnt)) != NULL_ROT) {
rev_rot = reverse_rotation(rot);
result.push_back(rot);
perform_rotation(&cube, rev_rot);
k = kh_get_cube(visited_states, cube);
rot_cnt = kh_val(visited_states, k);
}
std::reverse(result.begin(), result.end());
return result;
}
std::vector<rotations> Solver::solve(const cube_t cube) {
cube_t state = cube;
cube_t new_state;
khiter_t k;
rot_cnt_t rot_cnt;
uint16_t cur_cnt;
int rot, ret;
bool found_solution = false;
std::priority_queue<qentry_t, std::vector<qentry_t>, Comp> pq;
kh_clear_cube(visited_states);
k = kh_put_cube(visited_states, state, &ret);
kh_val(visited_states, k) = build_rot_cnt(NULL_ROT, 0);
pq.push({state, heuristic(cube, 0)});
while (!found_solution) {
auto cur = pq.top();
pq.pop();
state = cur.first;
// std::cerr << "Current state:\n";
// dump_cube_grid(&state);
k = kh_get_cube(visited_states, state);
cur_cnt = get_cnt(kh_val(visited_states, k));
for (rot = ROT_R; rot < NULL_ROT; rot++) {
new_state = state;
perform_rotation(&new_state, (rotations)rot);
k = kh_get_cube(pruning_table, new_state);
/* Found the cube in pruning table! We got it :D */
if (k != kh_end(pruning_table)) {
state = new_state;
found_solution = true;
k = kh_put_cube(visited_states, new_state, &ret);
kh_val(visited_states, k) = build_rot_cnt(rot, cur_cnt+1);
break;
}
k = kh_get_cube(visited_states, new_state);
/* This state was already visited.
* Maybe we found a shorter path? */
if (k != kh_end(visited_states)) {
rot_cnt = kh_val(visited_states, k);
if (get_cnt(rot_cnt) > cur_cnt + 1) {
kh_val(visited_states, k) = build_rot_cnt(rot, cur_cnt+1);
}
}
/* This is a new unvisited state! */
else {
k = kh_put_cube(visited_states, new_state, &ret);
kh_val(visited_states, k) = build_rot_cnt(rot, cur_cnt+1);
pq.push({new_state, heuristic(new_state, cur_cnt+1)});
}
}
}
std::cerr << "Found solution!\n" << "\n";
auto res = retrieve_solution(state);
auto prun_res = get_solve_pruning(state);
//std::cerr << prun_res.size() << "\n";
res.insert(res.end(), prun_res.begin(), prun_res.end());
return res;
}
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