Please Forward: Ruby Quiz Submission

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From: Omari Stephens <xsdg@mit.edu>
Date: December 2, 2007 9:28:10 PM CST
To: submission@rubyquiz.com
Subject: Please Forward: Ruby Quiz Submission

A solution to quiz #148

class String; def flatten_infix(foo); self; end; end
class Array
        def flatten_infix(up_op = :top)
                op = self[1]
                flat = self.map {|el| el.flatten_infix(op)}.join(" ")

                if($ops[up_op] < $ops[op])
                        flat = "(" + flat + ")"
                else
                        flat
                end
        end
end

$ops = {'*' => 0, '/' => 0, '+' => 1, '-' => 1, :top => 2}
puts ARGV[0].split.inject() {
        >stack, el|
        stack << if($ops.has_key?(el))
                [stack.pop, el, stack.pop].reverse
        else
                el
        end
        }.first.flatten_infix

--xsdg

···

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