From: James Edward Gray II <james@...>
Date: 2004-11-20T02:27:07+09:00
Subject: Re: Countdown (#7)

(redirected to Ruby Talk by JEG2)

On Nov 19, 2004, at 8:17 AM, Clark wrote:

> Hi James,
>
> Thanks for running the quiz.

My pleasure.  Thanks for following the quiz and thank for the 
corrections below.

James Edward Gray II

>> If you would like to see a very simple, if slow,
>> solution to the problem, have a look at Junghyun Kim's
>> submission.
>
> There is a problem with Junghyun's solution.  I tried it
> with target 101 source 100, 3, 3, 17 and it returned the
> solution (17.0/(3.0-3.0))/100.0, which contains a division
> by zero.
>
>> As an aside, I'm not convinced the yields to "op1" and
>> "op2" are needed.  I commented them out and was unable
>> to produce a failure, but it's possible I just didn't try
>> the right tests.
>
> The yields to "op1" and "op2" are needed in Brian's solution.
> They are the ones that make it possible to return a solution
> that contains a subset of the source numbers.  Try the
> 101, [100, 3, 3, 17] example with those yields commented out
> and you will see.
>
> This was the first week, that I tried it.  All my solutions
> were painfully slow.  Hopefully this week I'll do better.
>
> Clark