Class: SudokuBuilder::Solver

Inherits:
SudokuBuilder show all
Defined in:
lib/sudoku_builder/solver.rb

Constant Summary

Constants included from SudokuBuilder

VERSION

Instance Method Summary collapse

Methods included from SudokuBuilder

#new

Constructor Details

#initialize(sudoku) ⇒ Solver

Returns a new instance of Solver.



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# File 'lib/sudoku_builder/solver.rb', line 7

def initialize(sudoku)
  @sud = sudoku
  @pristine = sudoku
  @used = @sud.dup
end

Instance Method Details

#solve ⇒ Object

solve any given sudoku. If the sudoku is empty, it will build a complete one.



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# File 'lib/sudoku_builder/solver.rb', line 14

def solve
  t = 0 ; o = 0
  key = 0                               # main key variable.
  loop do
    if @sud[key].class == Array         # skips pre-filled numbers.
      c = [] ; r = [] ; g = []          # build values for current grid, row, column.
      build_crg(key,c,r,g,@sud)              # updates the relevant variables for check.
      @sud[key] = []                    # makes a fresh possibilities array.
      for i in 1..9
        if check?(i, c,r,g) &&
          !@used[key].include?(i)   # checks for possible numbers.
          @sud[key] << i
        end
      end
      if @sud[key].count == 0           # backtrack if no possibilities.
        key -= 1
      else
        use = @sud[key].sample          # pick a random possibility.
        @sud[key]   = [use]             # uses the possibility.
        @used[key] << use               # also puts it into the used array.
        key += 1
      end
      if key == 0 || t > 104            # resets everything if we've reached a high amount
        @sud.each { |k,v| @sud[k] = [] } # of run throughs, or the key has wound down to 0.
        @used = @sud.dup
        key = 0 ; t = 0
      end
    else
      key += 1
    end
    break if key == 81                  # break if we've reached the last value.
    t += 1 ; o += 1                     # add the reporting variables
    break if o > 1000000                # there is the possibility to be given an
    # unsolvable puzzle, this breaks if the number
    # of run throughs is really really high.
  end
  Builder.new(@sud)
end