Title
Sorting Balls and Water: Equivalence and Computational Complexity.
Abstract
Various forms of sorting problems have been studied over the years. Recently, two kinds of sorting puzzle apps are popularized. In these puzzles, we are given a set of bins filled with colored units, balls or water, and some empty bins. These puzzles allow us to move colored units from a bin to another when the colors involved match in some way or the target bin is empty. The goal of these puzzles is to sort all the color units in order. We investigate computational complexities of these puzzles. We first show that these two puzzles are essentially the same from the viewpoint of solvability. That is, an instance is sortable by ball-moves if and only if it is sortable by water-moves. We also show that every yes-instance has a solution of polynomial length, which implies that these puzzles belong to in NP. We then show that these puzzles are NP-complete. For some special cases, we give polynomial-time algorithms. We finally consider the number of empty bins sufficient for making all instances solvable and give non-trivial upper and lower bounds in terms of the number of filled bins and the capacity of bins.
Year
DOI
Venue
2022
10.4230/LIPIcs.FUN.2022.16
Fun with Algorithms (FUN)
DocType
Citations 
PageRank 
Conference
0
0.34
References 
Authors
0
10
Name
Order
Citations
PageRank
Takehiro Ito100.68
Jun Kawahara201.01
Shin-ichi Minato372584.72
Yota Otachi401.69
Toshiki Saitoh500.68
Akira Suzuki662.78
Ryuhei Uehara752875.38
Takeaki Uno801.01
Katsuhisa Yamanaka901.01
Ryo Yoshinaka1002.03