solver.rb

class Solver
  def initialize(open_char, close_char)
    @open_char  = open_char
    @close_char = close_char
    @count = 0
  end

  def run(string)
    chars = string.split("")
    chars.each do |char|
      case char
      when @open_char
        open
      when @close_char
        close
      else
        raise "invalid charactor detected"
      end
    end

    if @count == 0
      p "対応がとれている"
    else
      p "対応がとれていない"
    end
  end

  def open
    @count += 1
  end

  def close
    @count -= 1
    if @count < 0
      raise "invalid format"
    end
  end
end

Solver.new("「", "」").run("「」「「「」「」」「」「「「」」「」「「「」」「」」「「」「「」」「「」「「」」」「「」「「」「「「」」「」」」」」」」")