Sudoku

puzzles.txt

105802000090076405200400819019007306762083090000061050007600030430020501600308900
005030081902850060600004050007402830349760005008300490150087002090000600026049503
105802000090076405200400819019007306762083090000061050007600030430020501600308900
005030081902850060600004050007402830349760005008300490150087002090000600026049503
290500007700000400004738012902003064800050070500067200309004005000080700087005109
080020000040500320020309046600090004000640501134050700360004002407230600000700450
608730000200000460000064820080005701900618004031000080860200039050000100100456200
370000001000700005408061090000010000050090460086002030000000000694005203800149500

sudoku.rb

=begin



1) find cell 
2) test if empty
3) if the cell is empty
*4) horizontal test (num % 9) and vertical test (num % 9): use the test array (which is an array with the numbers 1 - 9) and compare (subtract) that from the arrays in the suduko nested array. find horizontal and vertical and push to a new array.
*5) box test: (divide by 27 && [num % 9]/3)
6) if the cell is not empty move to the next cell (start back at 2)
7) continue loop until no values in array are 0

=end

#require "sample_unsolved.txt"
def quit(message = '')
  puts message
  exit
end


class Sudoku

  attr_accessor :board_string

  def initialize(board_string)
    @board_array = string_to_array(board_string).map { |x| x.to_i }
  end
 
  def solve!
    until @board_array.include?(0) == false
      @board_array.each_with_index do |cell, i|
        excluded_numbers = []
        if cell == 0
          excluded_numbers += grab_row(i)
          excluded_numbers += grab_column(i)
          excluded_numbers += grab_box(i)
          excluded_numbers
          excluded_numbers.uniq!
          possible_numbers = (1..9).to_a-excluded_numbers 
          if possible_numbers.length == 1
            @board_array[i]=possible_numbers[0]
          end
        end
      end
    end
  end

  def board
    @board_array.join
  end

  def print_board
    temp_array = @board_array.dup
    print "#{temp_array[0..8].join(' ')}\n"
    print "#{temp_array[9..17].join(' ')}\n"
    print "#{temp_array[18..26].join(' ')}\n"
    print "#{temp_array[27..35].join(' ')}\n"
    print "#{temp_array[36..44].join(' ')}\n"
    print "#{temp_array[45..53].join(' ')}\n"
    print "#{temp_array[54..62].join(' ')}\n"
    print "#{temp_array[63..71].join(' ')}\n"
    print "#{temp_array[72..80].join(' ')}\n"
    print "\n\n"
  end

  def grab_row(target_index)
    return_array = []
    target_value = target_index / 9
    @board_array.each_with_index do |cell, index|
      return_array << cell if (index / 9 == target_value and cell != 0)
    end
    return_array
  end
  
  def grab_column(target_index)
    return_array = []
    target_value = target_index % 9
    @board_array.each_with_index do |cell, index|
      return_array << cell if (index % 9 == target_value and cell != 0)
    end
    return_array
  end


  def grab_box(target_index)
    return_array = []
    target_column_num = target_index % 9 / 3
    target_row_num = target_index / 27
    @board_array.each_with_index do |cell, i|
      return_array << cell if (i % 9 / 3 == target_column_num and i / 27 == target_row_num and cell != 0)
    end
    return_array
  end


  def string_to_array(string)
    string.split('')
  end


end
 
# The file has newlines at the end of each line, so we call
# String#chomp to remove them.
#board_string = File.readlines('sample.unsolved.txt').first.chomp
 

file = open("puzzles.txt", "r") 

file.each do |puzzle_string|
  # current_time = Time.now
  new_game = Sudoku.new(puzzle_string.chomp)
  new_game.print_board
  new_game.solve!
  new_game.print_board
end