Akari Solver in Copris

This page presents a Akari solver written in Copris, a Constraint Programming DSL (Domain-Specific Language) embedded in Scala. Akari is a puzzle game developed by Nikoli.

This Akari solver can find a solution of the given Akari puzzle.

Version 2.0

• Scala jar file: ../build/copris-puzzles-2.0.jar (1575981 bytes)
• Source file: ../build/copris-puzzles-src-2.0.zip (29766 bytes)

• Scala version 2.12 to be installed
  • Other Scala version is not binary compatible with version 2.12.
• Copris (included in the package)
• Sugar (included in the package)
• Sat4j Core (included in the package)

scala -cp copris-puzzles-2.0.jar akari.Solver input_file_name

• The format of the input file is explained below.

To check the uniqueness of the solutions, please use "-o multi" option.

scala -cp copris-puzzles-2.0.jar akari.Solver -o multi input_file_name

If you have a SAT solver (such as MiniSat, GlueMiniSat) installed on your computer, you can use it to get better performance. Specify the full path of the SAT solver program with "-s1" or "-s2" option.

scala -cp copris-puzzles-2.0.jar akari.Solver -o multi -s2 minisat input_file_name

Solver performance is measured on version 2.0.

• Copris solver was run on Intel Xeon 3.6Hz machine with:
  • Ubuntu Linux 20.04 (64 bit)
  • Java version "1.8.0_275", OpenJDK Runtime Environment (with "-Xmx2G" option)
  • Scala version 2.12.5
  • Copris version 2.3.1
  • Sugar version 2.3.4
• GlueMiniSat version 2.2.10 (with preprocessing) is used as a SAT solver.

The following shows the source code of the solver (Akari.scala).

 1:  /*
 2:   * Akari Solver in Copris
 3:   * by Naoyuki Tamura
 4:   * http://bach.istc.kobe-u.ac.jp/copris/puzzles/akari/
 5:   */
 6:  package akari
 7:  
 8:  import jp.kobe_u.copris._
 9:  import jp.kobe_u.copris.dsl._
10:  import puzzle._
11:  
12:  case class Akari(m: Int, n: Int, board: Seq[Seq[String]]) extends BoardPuzzle {
13:    def isBlank(cell: Cell) = at(cell) == "-"
14:    def isBlack(cell: Cell) = at(cell) == "x"
15:    val lines = {
16:      def seq(cell: Cell, dij: Cell): Seq[Cell] =
17:        if (! isCell(cell) || ! isBlank(cell)) Seq.empty
18:        else cell +: seq(move(cell, dij), dij)
19:      val vLines = for ((i,j) <- cells; if ! isCell((i-1,j)) || ! isBlank((i-1,j)))
20:                   yield seq((i,j), (1,0)).toSet
21:      val hLines = for ((i,j) <- cells; if ! isCell((i,j-1)) || ! isBlank((i,j-1)))
22:                   yield seq((i,j), (0,1)).toSet
23:      vLines ++ hLines
24:    }
25:    def show(sol: Set[Cell]) {
26:      for (i <- 0 until m) {
27:        for (j <- 0 until n) {
28:          val cell = (i,j)
29:          if (sol.contains(cell)) print(" @")
30:          else print(" " + at(cell))
31:        }
32:        println
33:      }
34:    }
35:  }
36:  
37:  object Solver extends BoardPuzzleSolver[Akari] {
38:    val name = "akari.Solver"
39:  
40:    def puzzleFactory(m: Int, n: Int, board: Seq[Seq[String]]) =
41:      Akari(m, n, board)
42:  
43:    def define = {
44:      for (cell <- puzzle.cells; if puzzle.isBlank(cell))
45:        int('x(cell), 0, 1)
46:      for ((cell) <- puzzle.cells; if puzzle.isNumber(cell)) {
47:        val xs = puzzle.adjCells(cell, puzzle.isBlank).map('x(_))
48:        add(Add(xs) === puzzle.num(cell))
49:      }
50:      val lines = puzzle.lines
51:      for (k <- 0 until lines.size) {
52:        int('l(k), 0, 1)
53:        add('l(k) === Add(lines(k).map(cell => 'x(cell))))
54:      }
55:      for (cell <- puzzle.cells; if puzzle.isBlank(cell)) {
56:        val ks = (0 until lines.size).filter(k => lines(k).contains(cell))
57:        add(Or(ks.map(k => 'l(k) === 1)))
58:      }
59:    }
60:  
61:    def showSolution {
62:      // Set of light cell positions
63:      val sol =
64:        for (cell <- puzzle.cells.toSet; if puzzle.isBlank(cell) && solution('x(cell)) > 0)
65:        yield cell
66:      if (quiet == 0) {
67:        println("Solution = " + sol)
68:        println("Size = " + sol.size)
69:        puzzle.show(sol)
70:      }
71:    }
72:  }

• It should be compiled with ../build/PuzzleSolver.scala.

This software is distributed under the BSD 3-Clause License. See LICENSE.

• Copris (Constraint Programming DSL embedded in Scala)
• Sugar (an award winning Constraint Solver)
  • Default constraint solver used in Copris
• Sat4j (SAT solver in Java)
  • Default SAT solver used in Copris
• Akari (by Nikoli)
• Wikipedia:Light Up (puzzle)
• http://www.janko.at/Raetsel/Akari/