deepbluecoder/min2phase

Rubik's Cube Solver. An optimized implementation of Kociemba's two-phase algorithm.

min2phase

• Rubik's Cube solver or scrambler.

two-phase algorithm

• See Kociemba's page

Improvements comparing to conventional two-phase algorithm

Conventional two-phase algorithm only find (sub-)optimal solutions to <U,R2,F2,D,L2,B2>. However, If we are able to find more phase1 solutions within a limited depth, the probability of finding a short solution will be increased.

• Try different axes: The target of phase1 can be either <U,R2,F2,D,L2,B2>, <U2,R,F2,D2,L,B2>, or <U2,R2,F,D2,L2,B>.
• Try the inverse of the state: We will try to solve the inverse state simultaneously to find more phase1 solutions.
• Try pre-scramble: We can also use pre-scramble technique (which is widely used in fewest-move challenge) to find more phase1 solutions.

Benchmark

• Memory: ~1M with twist-flip-pruning (TFP) table, ~0.7M without TFP table, ~40M with Full table. See Search.java line 28.

• Average solving time (CPU: Intel Core i7-2670QM. Flag: F=Full P1 table, T=TFP table, A=three axes, I=inverse, P=pre-scramble. Kociemba: Kociemba's twophase.jar):

  Flag	Unlimited	21 moves	20 moves
  Kociemba	45 ms	70 ms	>1000 ms
  TAIP	2.2 ms	2.6 ms	16 ms
  FAIP	1.8 ms	1.8 ms	2.5 ms

• Initialization Time: 150 ms without TFP table, 220 ms with TFP table, 12 s with Full table.

File Description

• Tools.java Many useful functions, can be excluded.
• Util.java Definitions and some math tools.
• CubieCube.java CubieCube, see kociemba's page.
• CoordCube.java Only for generating tables.
• Search.java Main.
• MainProgram.java GUI version.
• pruningValue.txt For checking whether the pruning table is generated correctly.

License GPLv3

Copyright (C) 2015  Shuang Chen

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, either version 3 of the License, or
(at your option) any later version.

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 <http://www.gnu.org/licenses/>.