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min2phase

  • Rubik's Cube solver or scrambler. Build Status

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/>.

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

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  • Java 99.4%
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