第2回 ESMオフラインどう書く（その2）

esm_offline_realtime2.rb

class Star
  BASE = 'ABCDEFGHIJ'.chars
  LINES = [
    ['A', 'F', 'G', 'D'],
    ['B', 'J', 'F', 'E'],
    ['C', 'I', 'J', 'A'],
    ['D', 'H', 'I', 'B'],
    ['E', 'G', 'H', 'C']
  ]

  def initialize(sample)
    @sample = sample
    @converted_base = 'WWWWWRRRRR'.chars
  end

  def solve
    @sample.chars.each do |char|
      change!(base_index(char))
      LINES.each do |line|
        if i = line.index(char)
          i / (line.size / 2) < 1 ? check_sequence(i, i + 1, line) : check_sequence(i, i - 1, line)
        end
      end
    end
    @converted_base.join
  end

  private

  def check_sequence(current, other, line)
    if current - other < 0
      next_index, end_of_line = 1, line.size - 1
    else
      next_index, end_of_line = -1, 0
    end

    if @converted_base[base_index(line[current])] == @converted_base[base_index(line[other])]
      unless (current - other).abs == 1
        target = current + next_index
        until target == other
          change!(base_index(line[target])) unless @converted_base[base_index(line[current])] == @converted_base[base_index(line[target])]
          target += next_index
        end
      else
        return
      end
    end
    other == end_of_line ? return : check_sequence(current, other + next_index, line)
  end

  def base_index(char)
    BASE.index(char)
  end

  def change!(index)
    @converted_base[index] = @converted_base[index] == 'R' ? 'W' : 'R'
  end
end

def test(sample, result)
  p Star.new(sample).solve == result
end

test("A", "RWWWWRRRRR")
test("F", "WWWWWWWRRW")
test("J", "WWWWWWRRWW")
test("AA", "WWWWWWWRWW")
test("IC", "WWRWWRRRWW")
test("FC", "WWRWWWWRRW")
test("AE", "RWWWRRRRRR")
test("GJ", "WWWWWWWWWW")
test("CCB", "WRWWWRWWWR")
test("BEF", "WRWWRWWRRR")
test("JGD", "WWWRWWWWWW")
test("IHCC", "WWWWWRWWWW")
test("AIDD", "RWWWWRRWWR")
test("IJFA", "RWWWWWWWWW")
test("ABCDE", "RRRRRRRRRR")
test("ICEBA", "RRRWRRRRRR")
test("DAHHD", "RWWWWRWWWR")
test("GJIJC", "WWRWWWWWRR")
test("FGHIJ", "WWWWWWWWRR")
test("HJICGA", "RWRWWRRRRR")
test("IBCIGC", "WRWWWWWWWW")
test("BIJJJB", "WWWWWWRWWW")
test("DCBCHGD", "WRWWWWWRRW")
test("JEABDHD", "RRWWRRRWRR")
test("JHFADHE", "RWWRRRRRWW")
test("HDGGDBIB", "WWWWWWWWWW")
test("IIDIHCCG", "WWWRWRRWWW")
test("BBFBICIE", "WRRWRRRWWW")
test("HJHCFBJGG", "WRRWWWWRRW")
test("AJJIEAAII", "RWWWRWWWWR")
test("AIDHJFGAE", "WWWRRWWWWW")
test("FGBGHCBHJJ", "WWRWWWWRRW")
test("EFIGIGGHHJ", "WWWWRRRWWR")
test("HGAFDIFFFF", "RWWRWRRRRW")
test("AABBCCDDEE", "WWWWWWWWWW")
test("ABCDEFGHIJ", "RRRRRWWWWW")
test("FGHIJABCDE", "RRRRRRRRRR")