PleaseForward: Ruby QuizSubmission

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From: "Rene Koning" <rene.koning@gmail.com>
Date: April 10, 2007 5:52:08 AM CDT
To: submission@rubyquiz.com
Subject: PleaseForward: Ruby QuizSubmission

My contribution to Quiz 119:

class Operators
OPS = ['','+','-']
attr_reader :operators

def initialize(size)
  @operators = [0] * size
end

def next_operator(n = 0)
  if @operators[n] < (OPS.size - 1)
   @operators[n] += 1
  else
   @operators[n] = 0
   next_operator(n + 1)
  end
end
end

class Equation
NUM = [1,2,3,4,5,6,7,8,9]
attr_reader :string

def initialize(operators)
  @string = NUM.zip(operators.operators.map { |o| Operators::OPS[o]}.flatten.compact).join('')
end

def answer
  eval(@string)
end
end

tested = 0
found = 0
match = 100

ops = Operators.new(Equation::NUM.size-1)
(Operators::OPS.size**(Equation::NUM.size-1)-1).times do
eq = Equation.new(ops)
answer = eq.answer

puts "************************" if answer == match
puts "#{eq.string} = #{answer}"
puts "************************" if answer == match

ops.next_operator
tested += 1
found += 1 if answer == match
end

puts "#{tested} equations tested, #{found} evaluated to #{match}"

···

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