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Fwd: Ruby Quiz #148

Dave Pederson

12/3/2007 2:47:00 AM

Note: parts of this message were removed by the gateway to make it a legal Usenet post.

Solution to quiz #148.
Thanks,

-Dave
---------- Forwarded message ----------
From: Dave Pederson <dave.pederson.ruby@gmail.com>
Date: Nov 30, 2007 7:26 PM
Subject: Ruby Quiz #148
To: dave.pederson.ruby@gmail.com


#!/usr/bin/env ruby

op = %w{ + - / * }
pm = %w{ + - }

postfixes = ["2 3 5 + *",
"1 56 35 + 16 9 - / +",
"56 34 213.7 + * 678 -",
"5 9 * 8 7 4 6 + * 2 1 3 * + * + *"]

puts
postfixes.each do |postfix|
stack = []
postfix.split.each do |c|
if op.include?(c)
second, first = stack.pop, stack.pop
if pm.include?(c)
stack.push "(#{first} #{c} #{second})"
else
stack.push "#{first} #{c} #{second}"
end
else
stack.push(c)
end
end
infix = stack.pop
if (infix[0] == 40 && infix[infix.size-1] == 41)
infix = infix[1, infix.size-2]
end
puts "postfix = #{postfix}"
puts "infix = #{infix}"
puts
end
4 Answers

Michael Boutros

12/3/2007 3:17:00 AM

0

I've looked at a lot of solutions for this quiz today and I have to say
I like yours the most. Good work :)
--
Posted via http://www.ruby-....

James Gray

12/3/2007 4:10:00 AM

0

On Dec 2, 2007, at 9:17 PM, Michael Boutros wrote:

> I've looked at a lot of solutions for this quiz today and I have to
> say
> I like yours the most. Good work :)

Since there was no name specified, I think all solvers should assume
he was talking to you. ;)

James Edward Gray II

Ken Bloom

12/3/2007 4:38:00 AM

0

On Sun, 02 Dec 2007 21:47:29 -0500, Dave Pederson wrote:

> Note: parts of this message were removed by the gateway to make it a
> legal Usenet post.
>
> Solution to quiz #148.
> Thanks,
>
> -Dave
> ---------- Forwarded message ---------- From: Dave Pederson
> <dave.pederson.ruby@gmail.com> Date: Nov 30, 2007 7:26 PM
> Subject: Ruby Quiz #148
> To: dave.pederson.ruby@gmail.com
>
>
> #!/usr/bin/env ruby
>
> op = %w{ + - / * }
> pm = %w{ + - }
>
> postfixes = ["2 3 5 + *",
> "1 56 35 + 16 9 - / +",
> "56 34 213.7 + * 678 -",
> "5 9 * 8 7 4 6 + * 2 1 3 * + * + *"]
>
> puts
> postfixes.each do |postfix|
> stack = []
> postfix.split.each do |c|
> if op.include?(c)
> second, first = stack.pop, stack.pop
> if pm.include?(c)
> stack.push "(#{first} #{c} #{second})"
> else
> stack.push "#{first} #{c} #{second}"
> end
> else
> stack.push(c)
> end
> end
> infix = stack.pop
> if (infix[0] == 40 && infix[infix.size-1] == 41)
> infix = infix[1, infix.size-2]
> end
> puts "postfix = #{postfix}"
> puts "infix = #{infix}"
> puts
> end

This is incorrect:

postfix = 3 5 * 5 8 * /
infix = 3 * 5 / 5 * 8

It should be
infix = 3 * 5 / (5 * 8)

--Ken

--
Ken (Chanoch) Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu...

Dave Pederson

12/3/2007 7:46:00 AM

0

Note: parts of this message were removed by the gateway to make it a legal Usenet post.

Thanks for pointing that out. I was trying to minimize parentheses...looks
like i kinda hurried though it. Anyways, here was my first solution (minus
the bonus points):

#!/usr/bin/env ruby

op = %w{ + - * / }
postfixes = ["2 3 5 + *",
"1 56 35 + 16 9 - / +",
"56 34 213.7 + * 678 -",
"5 9 * 8 7 4 6 + * 2 1 3 * + * + *",
"3 5 * 5 8 * /"]

postfixes.each do |postfix|
stack = []
postfix.split.each do |c|
unless op.include? c
stack.push(c)
else
second, first = stack.pop, stack.pop
stack.push "( #{first} #{c} #{second} )"
end
end
puts "postfix = #{postfix}"
puts "infix = #{stack.pop}"
puts
end



On Dec 2, 2007 8:40 PM, Ken Bloom <kbloom@gmail.com> wrote:

> On Sun, 02 Dec 2007 21:47:29 -0500, Dave Pederson wrote:
>
> > Note: parts of this message were removed by the gateway to make it a
> > legal Usenet post.
> >
> > Solution to quiz #148.
> > Thanks,
> >
> > -Dave
> > ---------- Forwarded message ---------- From: Dave Pederson
> > <dave.pederson.ruby@gmail.com> Date: Nov 30, 2007 7:26 PM
> > Subject: Ruby Quiz #148
> > To: dave.pederson.ruby@gmail.com
> >
> >
> > #!/usr/bin/env ruby
> >
> > op = %w{ + - / * }
> > pm = %w{ + - }
> >
> > postfixes = ["2 3 5 + *",
> > "1 56 35 + 16 9 - / +",
> > "56 34 213.7 + * 678 -",
> > "5 9 * 8 7 4 6 + * 2 1 3 * + * + *"]
> >
> > puts
> > postfixes.each do |postfix|
> > stack = []
> > postfix.split.each do |c|
> > if op.include?(c)
> > second, first = stack.pop, stack.pop
> > if pm.include?(c)
> > stack.push "(#{first} #{c} #{second})"
> > else
> > stack.push "#{first} #{c} #{second}"
> > end
> > else
> > stack.push(c)
> > end
> > end
> > infix = stack.pop
> > if (infix[0] == 40 && infix[infix.size-1] == 41)
> > infix = infix[1, infix.size-2]
> > end
> > puts "postfix = #{postfix}"
> > puts "infix = #{infix}"
> > puts
> > end
>
> This is incorrect:
>
> postfix = 3 5 * 5 8 * /
> infix = 3 * 5 / 5 * 8
>
> It should be
> infix = 3 * 5 / (5 * 8)
>
> --Ken
>
> --
> Ken (Chanoch) Bloom. PhD candidate. Linguistic Cognition Laboratory.
> Department of Computer Science. Illinois Institute of Technology.
> http://www.iit.edu... <http://www.iit.edu/%7Ekb...
>
>