Title
Algorithms for solving Rubik's cubes
Abstract
The Rubik's Cube is perhaps the world's most famous and iconic puzzle, well-known to have a rich underlying mathematical structure (group theory). In this paper, we show that the Rubik's Cube also has a rich underlying algorithmic structure. Specifically, we show that the n×n×n Rubik's Cube, as well as the n×n× 1 variant, has a "God's Number" (diameter of the configuration space) of Θ(n2/ log n). The upper bound comes from effectively parallelizing standard Θ(n2) solution algorithms, while the lower bound follows from a counting argument. The upper bound gives an asymptotically optimal algorithm for solving a general Rubik's Cube in the worst case. Given a specific starting state, we show how to find the shortest solution in an n×O(1)×O(1) Rubik's Cube. Finally, we show that finding this optimal solution becomes NP-hard in an n×n× 1 Rubik's Cube when the positions and colors of some cubies are ignored (not used in determining whether the cube is solved).
Year
DOI
Venue
2011
10.1007/978-3-642-23719-5_58
ESA'11 Proceedings of the 19th European conference on Algorithms
Keywords
DocType
Volume
n rubik,optimal solution,general rubik,asymptotically optimal algorithm,shortest solution,solution algorithm,configuration space,log n,rich underlying mathematical structure,rich underlying algorithmic structure
Conference
abs/1106.5736
ISSN
Citations 
PageRank 
0302-9743
5
1.01
References 
Authors
8
5
Name
Order
Citations
PageRank
Erik D. Demaine14624388.59
Martin L. Demaine259284.37
Sarah Eisenstat3537.88
Anna Lubiw475395.36
Andrew Winslow59115.29