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puzzle_cube
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puzzle_cube
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/*
Copyright (C) 2018-2024 Geoffrey Daniels. https://gpdaniels.com/
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License only.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#ifndef GTL_GAME_PUZZLE_CUBE_HPP
#define GTL_GAME_PUZZLE_CUBE_HPP
// Summary: Solver for 3x3 puzzle cubes. [wip]
#if defined(_MSC_VER)
#pragma warning(push, 0)
#endif
#include <string>
#if defined(_MSC_VER)
#pragma warning(pop)
#endif
namespace gtl {
class puzzle_cube final {
public:
enum class face_type {
front = 0,
right = 1,
back = 2,
left = 3,
up = 4,
down = 5,
};
constexpr friend int operator+(const face_type face) {
return static_cast<int>(face);
}
enum class move_type {
front = static_cast<int>(face_type::front),
right = static_cast<int>(face_type::right),
back = static_cast<int>(face_type::back),
left = static_cast<int>(face_type::left),
up = static_cast<int>(face_type::up),
down = static_cast<int>(face_type::down),
middle = 6,
equatial = 7,
standing = 8,
x = 9,
y = 10,
z = 11,
};
constexpr friend int operator+(const move_type move) {
return static_cast<int>(move);
}
// Colours of faces.
enum class colour_type {
green = static_cast<int>(face_type::front),
red = static_cast<int>(face_type::right),
blue = static_cast<int>(face_type::back),
orange = static_cast<int>(face_type::left),
white = static_cast<int>(face_type::up),
yellow = static_cast<int>(face_type::down),
};
constexpr friend int operator+(const colour_type colour) {
return static_cast<int>(colour);
}
private:
// Layout of cube face_type:
// this->cubie[face index][y coord][x coord]
//
// U[0][0] U[0][1] U[0][2]
// U[1][0] U[1][1] U[1][2]
// U[2][0] U[2][1] U[2][2]
// L[0][0] L[0][1] L[0][2] F[0][0] F[0][1] F[0][2] R[0][0] R[0][1] R[0][2] B[0][0] B[0][1] B[0][2]
// L[1][0] L[1][1] L[1][2] F[1][0] F[1][1] F[1][2] R[1][0] R[1][1] R[1][2] B[1][0] B[1][1] B[1][2]
// L[2][0] L[2][1] L[2][2] F[2][0] F[2][1] F[2][2] R[2][0] R[2][1] R[2][2] B[2][0] B[2][1] B[2][2]
// D[0][0] D[0][1] D[0][2]
// D[1][0] D[1][1] D[1][2]
// D[2][0] D[2][1] D[2][2]
// Definition of a cube, six faces each with nine cells.
colour_type cubie[6][3][3] = {
{ { colour_type::green, colour_type::green, colour_type::green }, { colour_type::green, colour_type::green, colour_type::green }, { colour_type::green, colour_type::green, colour_type::green }},
{ { colour_type::red, colour_type::red, colour_type::red }, { colour_type::red, colour_type::red, colour_type::red }, { colour_type::red, colour_type::red, colour_type::red }},
{ { colour_type::blue, colour_type::blue, colour_type::blue }, { colour_type::blue, colour_type::blue, colour_type::blue }, { colour_type::blue, colour_type::blue, colour_type::blue }},
{ { colour_type::orange, colour_type::orange, colour_type::orange }, { colour_type::orange, colour_type::orange, colour_type::orange }, { colour_type::orange, colour_type::orange, colour_type::orange }},
{ { colour_type::white, colour_type::white, colour_type::white }, { colour_type::white, colour_type::white, colour_type::white }, { colour_type::white, colour_type::white, colour_type::white }},
{ { colour_type::yellow, colour_type::yellow, colour_type::yellow }, { colour_type::yellow, colour_type::yellow, colour_type::yellow }, { colour_type::yellow, colour_type::yellow, colour_type::yellow }}
};
public:
void set_cubie(face_type face, int x, int y, colour_type colour) {
this->cubie[+face][y][x] = colour;
}
colour_type get_cubie(face_type face, int x, int y) const {
return this->cubie[+face][y][x];
}
public:
bool operator==(const puzzle_cube& other) const {
for (int f = 0; f < 6; ++f) {
for (int y = 0; y < 3; ++y) {
for (int x = 0; x < 3; ++x) {
if (this->cubie[f][y][x] != other.cubie[f][y][x]) {
return false;
}
}
}
}
return true;
}
bool operator!=(const puzzle_cube& other) const {
return !(*this == other);
}
public:
// Check if the cube is valid (aka it is solvable)
bool is_valid() const {
// This is a 2d bool array containing the color combinations possible in a corner.
bool edges[6][6] = {
{ 0, 1, 0, 1, 1, 1 },
{ 1, 0, 1, 0, 1, 1 },
{ 0, 1, 0, 1, 1, 1 },
{ 1, 0, 1, 0, 1, 1 },
{ 1, 1, 1, 1, 0, 0 },
{ 1, 1, 1, 1, 0, 0 }
};
// 3D array containing the possibible clockwise corner combinations.
bool corners[6][6][6] = {
{ { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 1 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 1, 0 }, { 0, 1, 0, 0, 0, 0 }, { 0, 0, 0, 1, 0, 0 } },
{ { 0, 0, 0, 0, 1, 0 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 1 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 1, 0, 0, 0 }, { 1, 0, 0, 0, 0, 0 } },
{ { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 1, 0 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 1 }, { 0, 0, 0, 1, 0, 0 }, { 0, 1, 0, 0, 0, 0 } },
{ { 0, 0, 0, 0, 0, 1 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 1, 0 }, { 0, 0, 0, 0, 0, 0 }, { 1, 0, 0, 0, 0, 0 }, { 0, 0, 1, 0, 0, 0 } },
{ { 0, 0, 0, 1, 0, 0 }, { 1, 0, 0, 0, 0, 0 }, { 0, 1, 0, 0, 0, 0 }, { 0, 0, 1, 0, 0, 0 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 0 } },
{ { 0, 1, 0, 0, 0, 0 }, { 0, 0, 1, 0, 0, 0 }, { 0, 0, 0, 1, 0, 0 }, { 1, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 0 } }
};
int up1[4] = { 7, 5, 1, 3 };
int down1[4] = { 1, 5, 7, 3 };
int up2[4] = { 8, 2, 0, 6 };
int down2[4] = { 2, 8, 6, 0 };
// Check the totals.
int totals[6] = { 0, 0, 0, 0, 0, 0 };
for (int f = 0; f < 6; ++f) {
for (int y = 0; y < 3; ++y) {
for (int x = 0; x < 3; ++x) {
if (++totals[+cubie[f][y][x]] > 9) {
return false;
}
}
}
}
// Check the centers
if (cubie[+face_type::up][1][1] == colour_type::white) {
// Check the colors anti-clockwise around.
if (!(+cubie[+face_type::right][1][1] == (+cubie[+face_type::front][1][1] + 1) % 4 &&
+cubie[+face_type::back][1][1] == (+cubie[+face_type::right][1][1] + 1) % 4 &&
+cubie[+face_type::left][1][1] == (+cubie[+face_type::back][1][1] + 1) % 4 &&
+cubie[+face_type::front][1][1] == (+cubie[+face_type::left][1][1] + 1) % 4))
{
return false;
}
}
if (cubie[+face_type::up][1][1] == colour_type::yellow) {
// Check the colors clockwise around.
if (!(+cubie[+face_type::left][1][1] == (+cubie[+face_type::front][1][1] + 1) % 4 &&
+cubie[+face_type::back][1][1] == (+cubie[+face_type::left][1][1] + 1) % 4 &&
+cubie[+face_type::right][1][1] == (+cubie[+face_type::back][1][1] + 1) % 4 &&
+cubie[+face_type::front][1][1] == (+cubie[+face_type::right][1][1] + 1) % 4)
) {
return false;
}
}
if (cubie[+face_type::right][1][1] == colour_type::white) {
if (!(+cubie[+face_type::front][1][1] == (+cubie[+face_type::up][1][1] + 1) % 4 &&
+cubie[+face_type::up][1][1] == (+cubie[+face_type::back][1][1] + 1) % 4 &&
+cubie[+face_type::back][1][1] == (+cubie[+face_type::down][1][1] + 1) % 4 &&
+cubie[+face_type::down][1][1] == (+cubie[+face_type::front][1][1] + 1) % 4)
) {
return false;
}
}
if (cubie[+face_type::right][1][1] == colour_type::yellow) {
if (!(+cubie[+face_type::back][1][1] == (+cubie[+face_type::up][1][1] + 1) % 4 &&
+cubie[+face_type::up][1][1] == (+cubie[+face_type::front][1][1] + 1) % 4 &&
+cubie[+face_type::front][1][1] == (+cubie[+face_type::down][1][1] + 1) % 4 &&
+cubie[+face_type::down][1][1] == (+cubie[+face_type::back][1][1] + 1) % 4)
) {
return false;
}
}
if (cubie[+face_type::front][1][1] == colour_type::white) {
if (!(+cubie[+face_type::left][1][1] == (+cubie[+face_type::up][1][1] + 1) % 4 &&
+cubie[+face_type::up][1][1] == (+cubie[+face_type::right][1][1] + 1) % 4 &&
+cubie[+face_type::right][1][1] == (+cubie[+face_type::down][1][1] + 1) % 4 &&
+cubie[+face_type::down][1][1] == (+cubie[+face_type::left][1][1] + 1) % 4)
) {
return false;
}
}
if (cubie[+face_type::front][1][1] == colour_type::yellow) {
if (!(+cubie[+face_type::right][1][1] == (+cubie[+face_type::up][1][1] + 1) % 4 &&
+cubie[+face_type::up][1][1] == (+cubie[+face_type::left][1][1] + 1) % 4 &&
+cubie[+face_type::left][1][1] == (+cubie[+face_type::down][1][1] + 1) % 4 &&
+cubie[+face_type::down][1][1] == (+cubie[+face_type::right][1][1] + 1) % 4)
) {
return false;
}
}
// Check the edges
// First check the up slice
for (int i = 0; i < 4; i++) {
// Check if top center of each face, combined with the corresponding up square is possible.
if (edges[+cubie[i][0][1]][+cubie[+face_type::up][up1[i]/3][up1[i]%3]] && edges[+cubie[+face_type::up][up1[i]/3][up1[i]%3]][+cubie[i][0][1]]) {
//If so, set them to false so there can't be a second.
edges[+cubie[i][0][1]][+cubie[+face_type::up][up1[i]/3][up1[i]%3]] = 0;
edges[+cubie[+face_type::up][up1[i]/3][up1[i]%3]][+cubie[i][0][1]] = 0;
}
else {
return false;
}
}
// Then the equatial slice
for (int i = 0; i < 4; i++) {
//check if square 5 (center right) of every face, combined with square 3 (center left) of the next face.
if (edges[+cubie[i][1][2]][+cubie[(i + 1) % 4][1][0]] && edges[+cubie[(i + 1) % 4][1][0]][+cubie[i][1][2]]) {
//If so, set them to false so there can't be a second.
edges[+cubie[i][1][2]][+cubie[(i + 1) % 4][1][0]] = 0;
edges[+cubie[(i + 1) % 4][1][0]][+cubie[i][1][2]] = 0;
}
else {
return false;
}
}
// Then the down slice
for (int i = 0; i < 4; i++) {
// Check if square 7 (down center) of each face, combined with the corresponding down square is possible.
if (edges[+cubie[i][2][1]][+cubie[+face_type::down][down1[i]/3][down1[i]%3]] && edges[+cubie[+face_type::down][down1[i]/3][down1[i]%3]][+cubie[i][2][1]]) {
// If so, set them to false so there can't be a second.
edges[+cubie[i][2][1]][+cubie[+face_type::down][down1[i]/3][down1[i]%3]] = 0;
edges[+cubie[+face_type::down][down1[i]/3][down1[i]%3]][+cubie[i][2][1]] = 0;
}
else {
return false;
}
}
// Next check the corners
// First the up slice
for (int i = 0; i < 4; i++) {
// Check if square 2 (top right) of each face, combined with the corresponding up square, combined with square 0 of the next face is possible.
// Repeat for every possible starting point
if (
corners[+cubie[i][0][2]][+cubie[+face_type::up][up2[i]/3][up2[i]%3]][+cubie[(i + 1) % 4][0][0]] &&
corners[+cubie[+face_type::up][up2[i]/3][up2[i]%3]][+cubie[(i + 1) % 4][0][0]][+cubie[i][0][2]] &&
corners[+cubie[(i + 1) % 4][0][0]][+cubie[i][0][2]][+cubie[+face_type::up][up2[i]/3][up2[i]%3]]
) {
corners[+cubie[i][0][2]][+cubie[+face_type::up][up2[i]/3][up2[i]%3]][+cubie[(i + 1) % 4][0][0]] = 0;
corners[+cubie[+face_type::up][up2[i]/3][up2[i]%3]][+cubie[(i + 1) % 4][0][0]][+cubie[i][0][2]] = 0;
corners[+cubie[(i + 1) % 4][0][0]][+cubie[i][0][2]][+cubie[+face_type::up][up2[i]/3][up2[i]%3]] = 0;
}
else {
return false;
}
}
// Then the down slice
for (int i = 0; i < 4; i++) {
// Check if square 8 (down right) of each face, combined with the corresponding down square, combined with square 6 of the next face is possible.
// Repeat for every possible starting point
if (
corners[+cubie[i][2][2]][+cubie[(i + 1) % 4][2][0]][+cubie[+face_type::down][down2[i]/3][down2[i]%3]] &&
corners[+cubie[(i + 1) % 4][2][0]][+cubie[+face_type::down][down2[i]/3][down2[i]%3]][+cubie[i][2][2]] &&
corners[+cubie[+face_type::down][down2[i]/3][down2[i]%3]][+cubie[i][2][2]][+cubie[(i + 1) % 4][2][0]]
) {
corners[+cubie[i][2][2]][+cubie[(i + 1) % 4][2][0]][+cubie[+face_type::down][down2[i]/3][down2[i]%3]] = 0;
corners[+cubie[(i + 1) % 4][2][0]][+cubie[+face_type::down][down2[i]/3][down2[i]%3]][+cubie[i][2][2]] = 0;
corners[+cubie[+face_type::down][down2[i]/3][down2[i]%3]][+cubie[i][2][2]][+cubie[(i + 1) % 4][2][0]] = 0;
}
else {
return false;
}
}
return true;
}
// Check if the cube is solved.
bool is_solved() const {
for (int f = 0; f < 6; ++f) {
for (int y = 0; y < 3; ++y) {
for (int x = 0; x < 3; ++x) {
if (this->cubie[f][y][x] != this->cubie[f][1][1]) {
return false;
}
}
}
}
return true;
}
public:
// Apply a single move to the cube, optionally multiple times.
void apply_moves(const move_type& move, const int turns = 1, std::string* record = nullptr) {
constexpr static const auto cycle = [](colour_type& first, colour_type& second, colour_type& third, colour_type& fourth) {
const colour_type temp = first;
first = fourth;
fourth = third;
third = second;
second = temp;
};
const int minimal_clockwise_turns = ((turns % 4) < 0) ? ((turns % 4) + 4) : (turns % 4);
for (int turn = 0; turn < minimal_clockwise_turns; ++turn) {
switch (move) {
// Rotate a single face.
case move_type::front:
if (record) record->push_back('F');
// Turn the outsides of edges and corners.
cycle(this->cubie[1][0][0], this->cubie[5][0][2], this->cubie[3][2][2], this->cubie[4][2][0]);
cycle(this->cubie[1][1][0], this->cubie[5][0][1], this->cubie[3][1][2], this->cubie[4][2][1]);
cycle(this->cubie[1][2][0], this->cubie[5][0][0], this->cubie[3][0][2], this->cubie[4][2][2]);
// Turn the face.
cycle(this->cubie[0][0][0], this->cubie[0][0][2], this->cubie[0][2][2], this->cubie[0][2][0]);
cycle(this->cubie[0][0][1], this->cubie[0][1][2], this->cubie[0][2][1], this->cubie[0][1][0]);
break;
case move_type::right:
if (record) record->push_back('R');
// Turn the outsides of edges and corners.
cycle(this->cubie[0][2][2], this->cubie[4][2][2], this->cubie[2][0][0], this->cubie[5][2][2]);
cycle(this->cubie[0][1][2], this->cubie[4][1][2], this->cubie[2][1][0], this->cubie[5][1][2]);
cycle(this->cubie[0][0][2], this->cubie[4][0][2], this->cubie[2][2][0], this->cubie[5][0][2]);
// Turn the face.
cycle(this->cubie[1][0][0], this->cubie[1][0][2], this->cubie[1][2][2], this->cubie[1][2][0]);
cycle(this->cubie[1][0][1], this->cubie[1][1][2], this->cubie[1][2][1], this->cubie[1][1][0]);
break;
case move_type::back:
if (record) record->push_back('B');
// Turn the outsides of edges and corners.
cycle(this->cubie[1][0][2], this->cubie[4][0][0], this->cubie[3][2][0], this->cubie[5][2][2]);
cycle(this->cubie[1][1][2], this->cubie[4][0][1], this->cubie[3][1][0], this->cubie[5][2][1]);
cycle(this->cubie[1][2][2], this->cubie[4][0][2], this->cubie[3][0][0], this->cubie[5][2][0]);
// Turn the face.
cycle(this->cubie[2][0][0], this->cubie[2][0][2], this->cubie[2][2][2], this->cubie[2][2][0]);
cycle(this->cubie[2][0][1], this->cubie[2][1][2], this->cubie[2][2][1], this->cubie[2][1][0]);
break;
case move_type::left:
if (record) record->push_back('L');
// Turn the outsides of edges and corners.
cycle(this->cubie[0][0][0], this->cubie[5][0][0], this->cubie[2][2][2], this->cubie[4][0][0]);
cycle(this->cubie[0][1][0], this->cubie[5][1][0], this->cubie[2][1][2], this->cubie[4][1][0]);
cycle(this->cubie[0][2][0], this->cubie[5][2][0], this->cubie[2][0][2], this->cubie[4][2][0]);
// Turn the face.
cycle(this->cubie[3][0][0], this->cubie[3][0][2], this->cubie[3][2][2], this->cubie[3][2][0]);
cycle(this->cubie[3][0][1], this->cubie[3][1][2], this->cubie[3][2][1], this->cubie[3][1][0]);
break;
case move_type::up:
if (record) record->push_back('U');
// Turn the outsides of edges and corners.
cycle(this->cubie[0][0][0], this->cubie[3][0][0], this->cubie[2][0][0], this->cubie[1][0][0]);
cycle(this->cubie[0][0][1], this->cubie[3][0][1], this->cubie[2][0][1], this->cubie[1][0][1]);
cycle(this->cubie[0][0][2], this->cubie[3][0][2], this->cubie[2][0][2], this->cubie[1][0][2]);
// Turn the face.
cycle(this->cubie[4][0][0], this->cubie[4][0][2], this->cubie[4][2][2], this->cubie[4][2][0]);
cycle(this->cubie[4][0][1], this->cubie[4][1][2], this->cubie[4][2][1], this->cubie[4][1][0]);
break;
case move_type::down:
if (record) record->push_back('D');
// Turn the outsides of edges and corners.
cycle(this->cubie[0][2][0], this->cubie[1][2][0], this->cubie[2][2][0], this->cubie[3][2][0]);
cycle(this->cubie[0][2][1], this->cubie[1][2][1], this->cubie[2][2][1], this->cubie[3][2][1]);
cycle(this->cubie[0][2][2], this->cubie[1][2][2], this->cubie[2][2][2], this->cubie[3][2][2]);
// Turn the face.
cycle(this->cubie[5][0][0], this->cubie[5][0][2], this->cubie[5][2][2], this->cubie[5][2][0]);
cycle(this->cubie[5][0][1], this->cubie[5][1][2], this->cubie[5][2][1], this->cubie[5][1][0]);
break;
// Rotate a middle layer.
case move_type::middle:
if (record) record->push_back('M');
cycle(this->cubie[0][0][1], this->cubie[5][0][1], this->cubie[2][2][1], this->cubie[4][0][1]);
cycle(this->cubie[0][1][1], this->cubie[5][1][1], this->cubie[2][1][1], this->cubie[4][1][1]);
cycle(this->cubie[0][2][1], this->cubie[5][2][1], this->cubie[2][0][1], this->cubie[4][2][1]);
break;
case move_type::equatial:
if (record) record->push_back('E');
cycle(this->cubie[0][1][0], this->cubie[1][1][0], this->cubie[2][1][0], this->cubie[3][1][0]);
cycle(this->cubie[0][1][1], this->cubie[1][1][1], this->cubie[2][1][1], this->cubie[3][1][1]);
cycle(this->cubie[0][1][2], this->cubie[1][1][2], this->cubie[2][1][2], this->cubie[3][1][2]);
break;
case move_type::standing:
if (record) record->push_back('S');
cycle(this->cubie[1][0][1], this->cubie[5][1][2], this->cubie[3][2][1], this->cubie[4][1][0]);
cycle(this->cubie[1][1][1], this->cubie[5][1][1], this->cubie[3][1][1], this->cubie[4][1][1]);
cycle(this->cubie[1][2][1], this->cubie[5][1][0], this->cubie[3][0][1], this->cubie[4][1][2]);
break;
// Rotate the whole cube rather than just a face.
case move_type::x:
if (record) record->append(std::string(static_cast<std::string::size_type>(minimal_clockwise_turns), 'X'));
// Ignores left and right faces.
this->apply_moves(move_type::right, turns);
this->apply_moves(move_type::middle, 4 - turns);
this->apply_moves(move_type::left, 4 - turns);
// Now return rather than break as multiple turns are already handled by the recursive calls.
return;
case move_type::y:
if (record) record->append(std::string(static_cast<std::string::size_type>(minimal_clockwise_turns), 'Y'));
// Ignores up and down faces.
this->apply_moves(move_type::up, turns);
this->apply_moves(move_type::equatial, 4 - turns);
this->apply_moves(move_type::down, 4 - turns);
// Now return rather than break as multiple turns are already handled by the recursive calls.
return;
case move_type::z:
if (record) record->append(std::string(static_cast<std::string::size_type>(minimal_clockwise_turns), 'Z'));
// Ignores front and back faces.
this->apply_moves(move_type::front, turns);
this->apply_moves(move_type::standing, turns);
this->apply_moves(move_type::back, 4 - turns);
// Now return rather than break as multiple turns are already handled by the recursive calls.
return;
}
}
}
// Apply a series of moves to the cube.
bool apply_moves(const char* move_string, std::string* record = nullptr) {
if (move_string == nullptr) {
return true;
}
while (*move_string != 0) {
const char move_character = *move_string++;
switch (move_character) {
default: return false;
case 'U': this->apply_moves(move_type::up, 1, record); break;
case 'D': this->apply_moves(move_type::down, 1, record); break;
case 'L': this->apply_moves(move_type::left, 1, record); break;
case 'R': this->apply_moves(move_type::right, 1, record); break;
case 'F': this->apply_moves(move_type::front, 1, record); break;
case 'B': this->apply_moves(move_type::back, 1, record); break;
case 'M': this->apply_moves(move_type::middle, 1, record); break;
case 'E': this->apply_moves(move_type::equatial, 1, record); break;
case 'S': this->apply_moves(move_type::standing, 1, record); break;
case 'X': this->apply_moves(move_type::x, 1, record); break;
case 'Y': this->apply_moves(move_type::y, 1, record); break;
case 'Z': this->apply_moves(move_type::z, 1, record); break;
}
}
return true;
}
public:
// Check that there is a cross on the down face and all side faces have the correct centre and bottom cell.
bool validate_first_layer_cross() const {
bool valid = true;
// Check there is a cross of all the same colour on the down face of the cube.
valid &= (this->cubie[+face_type::down][0][1] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][1][0] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][1][2] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][2][1] == this->cubie[+face_type::down][1][1]);
// Check the side faces of the cross match the centre of their respective faces.
valid &= (this->cubie[+face_type::front][2][1] == this->cubie[+face_type::front][1][1]);
valid &= (this->cubie[+face_type::right][2][1] == this->cubie[+face_type::right][1][1]);
valid &= (this->cubie[+face_type::back][2][1] == this->cubie[+face_type::back][1][1]);
valid &= (this->cubie[+face_type::left][2][1] == this->cubie[+face_type::left][1][1]);
return valid;
}
// Check that the corners are all the same colour as the centre on the bottom face of the cube.
bool validate_first_layer_corners() const {
bool valid = true;
// Check the corners of the down face match the centre.
valid &= (this->cubie[+face_type::down][0][0] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][0][2] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][2][0] == this->cubie[+face_type::down][1][1]);
valid &= (this->cubie[+face_type::down][2][2] == this->cubie[+face_type::down][1][1]);
// Check the side faces of the corners match the centre of their respective faces.
valid &= (this->cubie[+face_type::front][2][0] == this->cubie[+face_type::front][1][1]);
valid &= (this->cubie[+face_type::front][2][2] == this->cubie[+face_type::front][1][1]);
valid &= (this->cubie[+face_type::right][2][0] == this->cubie[+face_type::right][1][1]);
valid &= (this->cubie[+face_type::right][2][2] == this->cubie[+face_type::right][1][1]);
valid &= (this->cubie[+face_type::back][2][0] == this->cubie[+face_type::back][1][1]);
valid &= (this->cubie[+face_type::back][2][2] == this->cubie[+face_type::back][1][1]);
valid &= (this->cubie[+face_type::left][2][0] == this->cubie[+face_type::left][1][1]);
valid &= (this->cubie[+face_type::left][2][2] == this->cubie[+face_type::left][1][1]);
return valid;
}
// Check that all the middle layer edges of the cube (front, right, back, left) are the same colour as the centre of their respective faces.
bool validate_middle_edges() const {
bool valid = true;
valid &= ((this->cubie[+face_type::front][1][0] == this->cubie[+face_type::front][1][1]) && (this->cubie[+face_type::front][1][2] == this->cubie[+face_type::front][1][1]));
valid &= ((this->cubie[+face_type::right][1][0] == this->cubie[+face_type::right][1][1]) && (this->cubie[+face_type::right][1][2] == this->cubie[+face_type::right][1][1]));
valid &= ((this->cubie[+face_type::back][1][0] == this->cubie[+face_type::back][1][1]) && (this->cubie[+face_type::back][1][2] == this->cubie[+face_type::back][1][1]));
valid &= ((this->cubie[+face_type::left][1][0] == this->cubie[+face_type::left][1][1]) && (this->cubie[+face_type::left][1][2] == this->cubie[+face_type::left][1][1]));
return valid;
}
// Check that there is a cross on the top layer.
bool validate_last_layer_cross() const {
bool valid = true;
// Check there is a cross of all the same colour on the up face of the cube.
valid &= (this->cubie[+face_type::up][0][1] == this->cubie[+face_type::up][1][1]);
valid &= (this->cubie[+face_type::up][1][0] == this->cubie[+face_type::up][1][1]);
valid &= (this->cubie[+face_type::up][1][2] == this->cubie[+face_type::up][1][1]);
valid &= (this->cubie[+face_type::up][2][1] == this->cubie[+face_type::up][1][1]);
return valid;
}
// Check that the edges of the cross on the top layer are correct.
bool validate_last_layer_edges() const {
bool valid = true;
// Check there is a cross of all the same colour on the up face of the cube.
valid &= (this->cubie[+face_type::front][0][1] == this->cubie[+face_type::front][1][1]);
valid &= (this->cubie[+face_type::right][0][1] == this->cubie[+face_type::right][1][1]);
valid &= (this->cubie[+face_type::back][0][1] == this->cubie[+face_type::back][1][1]);
valid &= (this->cubie[+face_type::left][0][1] == this->cubie[+face_type::left][1][1]);
return valid;
}
// Check that the corners of the top layer are the correct colour.
bool validate_last_layer_corner_positions() const {
bool valid = true;
// Check all corners of the up face are in the correct position.
puzzle_cube temp_cube = *this;
for (int i = 0; i < 4; ++i) {
valid &= (
(
(temp_cube.cubie[+face_type::front][0][2] == temp_cube.cubie[+face_type::front][1][1]) &&
(temp_cube.cubie[+face_type::right][0][0] == temp_cube.cubie[+face_type::right][1][1]) &&
(temp_cube.cubie[+face_type::up][2][2] == temp_cube.cubie[+face_type::up][1][1])
) || (
(temp_cube.cubie[+face_type::front][0][2] == temp_cube.cubie[+face_type::up][1][1]) &&
(temp_cube.cubie[+face_type::right][0][0] == temp_cube.cubie[+face_type::front][1][1]) &&
(temp_cube.cubie[+face_type::up][2][2] == temp_cube.cubie[+face_type::right][1][1])
) || (
(temp_cube.cubie[+face_type::front][0][2] == temp_cube.cubie[+face_type::right][1][1]) &&
(temp_cube.cubie[+face_type::right][0][0] == temp_cube.cubie[+face_type::up][1][1]) &&
(temp_cube.cubie[+face_type::up][2][2] == temp_cube.cubie[+face_type::front][1][1])
)
);
temp_cube.apply_moves(move_type::y);
}
return valid;
}
public:
// Transform the cube so that there is a cross on the down face.
bool solve_first_layer_cross(std::string* solution = nullptr) {
// Check if we are already done.
if (this->validate_first_layer_cross()) {
return true;
}
// The cross should be able to be solved max 4 rounds. One edge per round.
for (int i = 0; i < 4; ++i) {
const colour_type colour_right = cubie[+face_type::right][1][1];
const colour_type colour_down = cubie[+face_type::down][1][1];
// The four times that the piece is on the right face, and just needs spun into position
if ((cubie[+face_type::right][0][1] == colour_right) && (cubie[+face_type::up][1][2] == colour_down)) {
this->apply_moves("RR", solution);
}
else if (cubie[+face_type::right][1][2] == colour_right && cubie[+face_type::back][1][0] == colour_down) {
this->apply_moves("R", solution);
}
else if (cubie[+face_type::right][1][0] == colour_right && cubie[+face_type::front][1][2] == colour_down) {
this->apply_moves("RRR", solution);
}
else if (cubie[+face_type::right][2][1] == colour_right && cubie[+face_type::down][1][2] == colour_down) {
// Already correct.
}
// The four times that the piece is on the right face, but isn't in a nice orientation
else if (cubie[+face_type::right][0][1] == colour_down && cubie[+face_type::up][1][2] == colour_right) {
this->apply_moves("UFRRRFFF", solution);
}
else if (cubie[+face_type::right][1][2] == colour_down && cubie[+face_type::back][1][0] == colour_right) {
this->apply_moves("DBBBDDD", solution);
}
else if (cubie[+face_type::right][1][0] == colour_down && cubie[+face_type::front][1][2] == colour_right) {
this->apply_moves("DDDFD", solution);
}
else if (cubie[+face_type::right][2][1] == colour_down && cubie[+face_type::down][1][2] == colour_right) {
this->apply_moves("DDDFFFDRRR", solution);
}
// The four positions where it's on the top of the the middle slice, i.e. not on the right or on the left
else if (cubie[+face_type::up][2][1] == colour_right && cubie[+face_type::front][0][1] == colour_down) {
this->apply_moves("FRRRFFF", solution);
}
else if (cubie[+face_type::up][2][1] == colour_down && cubie[+face_type::front][0][1] == colour_right) {
this->apply_moves("UUURR", solution);
}
else if(cubie[+face_type::up][0][1] == colour_right && cubie[+face_type::back][0][1] == colour_down) {
this->apply_moves("BBBRB", solution);
}
else if(cubie[+face_type::up][0][1] == colour_down && cubie[+face_type::back][0][1] == colour_right) {
this->apply_moves("URR", solution);
}
// The four positions where it's on the bottom of the middle slice, i.e. not on the right or the left
else if (cubie[+face_type::down][0][1] == colour_right && cubie[+face_type::front][2][1] == colour_down) {
this->apply_moves("FFFRRR", solution);
}
else if (cubie[+face_type::down][0][1] == colour_down && cubie[+face_type::front][2][1] == colour_right) {
this->apply_moves("FFFDDDFD", solution);
}
else if (cubie[+face_type::down][2][1] == colour_right && cubie[+face_type::back][2][1] == colour_down) {
this->apply_moves("BR", solution);
}
else if (cubie[+face_type::down][2][1] == colour_down && cubie[+face_type::back][2][1] == colour_right) {
this->apply_moves("BDBBBDDD", solution);
}
// Now, the 8 positions where it's on the left hand face
else if (cubie[+face_type::up][1][0] == colour_right && cubie[+face_type::left][0][1] == colour_down) {
this->apply_moves("LLLDBDDDL", solution);
}
else if (cubie[+face_type::up][1][0] == colour_down && cubie[+face_type::left][0][1] == colour_right) {
this->apply_moves("UURR", solution);
}
else if (cubie[+face_type::back][1][2] == colour_right && cubie[+face_type::left][1][0] == colour_down) {
this->apply_moves("DBDDD", solution);
}
else if (cubie[+face_type::back][1][2] == colour_down && cubie[+face_type::left][1][0] == colour_right) {
this->apply_moves("DDLLLDD", solution);
}
else if (cubie[+face_type::front][1][0] == colour_right && cubie[+face_type::left][1][2] == colour_down) {
this->apply_moves("DDDFFFD", solution);
}
else if (cubie[+face_type::front][1][0] == colour_down && cubie[+face_type::left][1][2] == colour_right) {
this->apply_moves("DDLDD", solution);
}
else if (cubie[+face_type::down][1][0] == colour_down && cubie[+face_type::left][2][1] == colour_right) {
this->apply_moves("LLLDDLDD", solution);
}
else if (cubie[+face_type::down][1][0] == colour_right && cubie[+face_type::left][2][1] == colour_down) {
this->apply_moves("LLLDDDFFFD", solution);
}
else {
// Should never get here.
return false;
}
this->apply_moves("Y", solution);
}
return (this->validate_first_layer_cross());
}
// Transform the cube so that the down face is uniform.
bool solve_first_layer_corners(std::string* solution = nullptr) {
// Must start with a valid cross.
if (!validate_first_layer_cross()) {
return false;
}
// Check if we are already done.
if (this->validate_first_layer_corners()) {
return true;
}
for (int i = 0; i < 4 * 4; ++i) {
// Rotate first to allow us to continue if already set.
this->apply_moves("Y", solution);
// Check if the corner on the bottom cross is already done.
if (
(this->cubie[+face_type::down][0][0] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::left][2][2] == this->cubie[+face_type::left][1][1]) &&
(this->cubie[+face_type::front][2][0] == this->cubie[+face_type::front][1][1])
) {
continue;
}
// Search top layer for corner cubes (note correct colour could be on any side) and solve.
for (int k = 0; k < 4; ++k) {
if (
(this->cubie[+face_type::up][2][0] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::left][0][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::front][0][0] == this->cubie[+face_type::left][1][1])
) {
this->apply_moves("LLLULFUUFFF", solution);
break;
}
else if (
(this->cubie[+face_type::left][0][2] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::up][2][0] == this->cubie[+face_type::left][1][1]) &&
(this->cubie[+face_type::front][0][0] == this->cubie[+face_type::front][1][1])
) {
this->apply_moves("LLLUUUL", solution);
break;
}
else if (
(this->cubie[+face_type::front][0][0] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::up][2][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::left][0][2] == this->cubie[+face_type::left][1][1])
) {
this->apply_moves("FUFFF", solution);
break;
}
this->apply_moves("U", solution);
}
// Check if the corner on the bottom cross is done now.
if (
(this->cubie[+face_type::down][0][0] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::left][2][2] == this->cubie[+face_type::left][1][1]) &&
(this->cubie[+face_type::front][2][0] == this->cubie[+face_type::front][1][1])
) {
continue;
}
// Search bottom layer for twisted corners.
if (
(this->cubie[+face_type::left][2][2] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::down][0][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::front][2][0] == this->cubie[+face_type::left][1][1])
) {
this->apply_moves("LLLULFUFFFLLLULFUFFF", solution);
continue;
}
else if (
(this->cubie[+face_type::front][2][0] == this->cubie[+face_type::down][1][1]) &&
(this->cubie[+face_type::left][2][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::down][0][0] == this->cubie[+face_type::left][1][1])
) {
this->apply_moves("LLLULFUFFF", solution);
}
else {
// If not found anywhere displace the current.
this->apply_moves("FUFFF", solution);
}
}
return this->validate_first_layer_corners();
}
// Transform the cube so that the edges along the sides of the down face are correct.
bool solve_middle_edges(std::string* solution = nullptr) {
// Must start with a valid cross and corners.
if ((!validate_first_layer_cross()) || (!this->validate_first_layer_corners())) {
return false;
}
// Check if we are already done.
if (this->validate_middle_edges()) {
return true;
}
for (int i = 0; i < 4*4*4; ++i) {
// Rotate first to allow us to continue if already set.
this->apply_moves("Y", solution);
// Check if left and right middle cells are correct, if so go to next face.
if (
(this->cubie[+face_type::front][1][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::left][1][2] == this->cubie[+face_type::left][1][1]) &&
(this->cubie[+face_type::front][1][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::right][1][0] == this->cubie[+face_type::right][1][1])
) {
continue;
}
// Search for top middle cell to move into position.
for (int k = 0; k < 4; ++k) {
if (this->cubie[+face_type::front][0][1] == this->cubie[+face_type::front][1][1]) {
if (this->cubie[+face_type::up][2][1] == this->cubie[+face_type::left][1][1]) {
this->apply_moves("UUULLLULUFUUUFFF", solution);
break;
}
else if (this->cubie[+face_type::up][2][1] == this->cubie[+face_type::right][1][1]) {
this->apply_moves("URUUURRRUUUFFFUF", solution);
break;
}
}
this->apply_moves("U", solution);
}
// Check if left and right middle cells are correct, if so go to next face.
if (
(this->cubie[+face_type::front][1][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::left][1][2] == this->cubie[+face_type::left][1][1]) &&
(this->cubie[+face_type::front][1][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::right][1][0] == this->cubie[+face_type::right][1][1])
) {
continue;
}
// Otherwise just apply the left or right algorithm.
if (
(this->cubie[+face_type::front][1][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::left][1][2] == this->cubie[+face_type::left][1][1])
) {
this->apply_moves("URUUURRRUUUFFFUF", solution);
}
else {
this->apply_moves("UUULLLULUFUUUFFF", solution);
}
}
return this->validate_middle_edges();
}
// Transform the cube so that there is a cross on the top face.
bool solve_last_layer_cross(std::string* solution = nullptr) {
// Must start with a valid cross, corners, and edges.
if ((!validate_first_layer_cross()) || (!this->validate_first_layer_corners()) || (!this->validate_middle_edges())) {
return false;
}
// Check if we are already done.
if (this->validate_last_layer_cross()) {
return true;
}
// Calculate the number of times we need to apply a solving algorithm.
// There are three situations, "dot", "L", and "line", requiring 3, 2, and 1 applications.
int applications_required = 0;
// First check for a "dot".
if (
(this->cubie[+face_type::up][0][1] != this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][0] != this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][2] != this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][2][1] != this->cubie[+face_type::up][1][1])
) {
// Found a "dot".
applications_required = 3;
}
// Next check for an "L".
if (applications_required == 0) {
// Check 4 orientations of cube.
for (int i = 0; i < 4; ++i) {
if (
(this->cubie[+face_type::up][0][1] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][0] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][2] != this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][2][1] != this->cubie[+face_type::up][1][1])
) {
// Found an "L".
applications_required = 2;
break;
}
this->apply_moves("Y", solution);
}
}
// Next check for a "line".
if (applications_required == 0) {
// Check 2 orientations of cube.
for (int i = 0; i < 2; ++i) {
if (
(this->cubie[+face_type::up][0][1] != this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][0] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][1][2] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][2][1] != this->cubie[+face_type::up][1][1])
) {
// Found a "line".
applications_required = 1;
break;
}
this->apply_moves("Y", solution);
}
}
// Failed to find a solution.
if (applications_required == 0) {
return false;
}
// Apply the solving algorithm.
for (int i = 0; i < applications_required; ++i) {
this->apply_moves("FRURRRUUUFFFYY", solution);
}
return this->validate_last_layer_cross();
}
// Transform the cube so that the top face cross edges are in the correct location.
bool solve_last_layer_edges(std::string* solution = nullptr) {
// Must start with a valid cross, corners, edges, and last layer cross.
if ((!validate_first_layer_cross()) || (!this->validate_first_layer_corners()) || (!this->validate_middle_edges()) || (!this->validate_last_layer_cross())) {
return false;
}
// Check if we are already done.
if (this->validate_last_layer_edges()) {
return true;
}
// Loop around the cube 4 times potentially moving edges.
for (int i = 0; i < 4*4; ++i) {
if (this->cubie[+face_type::front][0][1] != this->cubie[+face_type::front][1][1]) {
this->apply_moves("RURRRURUURRRU", solution);
}
this->apply_moves("Y", solution);
}
return this->validate_last_layer_edges();
}
// Transform the cube so that the top face corners are in the correct position (but maybe not correct orientation).
bool solve_last_layer_corner_positions(std::string* solution = nullptr) {
// Must start with a valid cross, corners, edges, last layer cross, and last layer edges.
if ((!validate_first_layer_cross()) || (!this->validate_first_layer_corners()) || (!this->validate_middle_edges()) || (!this->validate_last_layer_cross()) || (!this->validate_last_layer_edges())) {
return false;
}
// Check if we are already done.
if (this->validate_last_layer_corner_positions()) {
return true;
}
// Find a correct corner.
bool none_correct = true;
for (int i = 0; i < 4; ++i) {
if (
(
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::right][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::up][1][1])
) || (
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::right][1][1])
)
|| (
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::right][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::front][1][1])
)
) {
none_correct = false;
break;
}
this->apply_moves("Y", solution);
}
if (none_correct) {
// Create a correct corner.
this->apply_moves("URUUULLLURRRUUUL", solution);
// Find a correct corner.
for (int i = 0; i < 4; ++i) {
if (
(
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::right][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::up][1][1])
) || (
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::front][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::right][1][1])
) || (
(this->cubie[+face_type::front][0][2] == this->cubie[+face_type::right][1][1]) &&
(this->cubie[+face_type::right][0][0] == this->cubie[+face_type::up][1][1]) &&
(this->cubie[+face_type::up][2][2] == this->cubie[+face_type::front][1][1])
)
) {
break;
}
this->apply_moves("Y", solution);
}
}
// Apply the algorithm (potentially twice).
this->apply_moves("URUUULLLURRRUUUL", solution);
if (!this->validate_last_layer_corner_positions()) {
this->apply_moves("URUUULLLURRRUUUL", solution);
}
return this->validate_last_layer_corner_positions();
}
// Transform the cube so that the top face corners are in the correct orientation.
bool solve_last_layer_corner_orientations(std::string* solution = nullptr) {
// Must start with a valid cross, corners, edges, last layer cross, last layer edges, and last layer corner positions.
if ((!validate_first_layer_cross()) || (!this->validate_first_layer_corners()) || (!this->validate_middle_edges()) || (!this->validate_last_layer_cross()) || (!this->validate_last_layer_edges()) || (!this->validate_last_layer_corner_positions())) {
return false;
}
// Check if we are already done.