From: Robert Dober <robert.dober@...>
Date: 2007-04-06T22:32:00+09:00
Subject: Re: [QUIZ] Getting to 100 (#119)

On 4/6/07, Ruby Quiz <james@grayproductions.net> wrote:
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> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
> by Gavin Kistner
>
> The NPR show "Car Talk" has regular quizzes that they call "Puzzlers"[1]. The
> one listed on their web site for March 12th[2] is titled "Getting to 100". In
> the quiz, you are supposed to write down the digits 1-9 in order, followed by "
> = 100", and then insert between them two minus symbols and one plus symbol (in
> any order) to make the formula correct. You aren't allowed to re-arrange digits,
> or do some toothpick math like combine two minus signs to make a plus. You must
> use every digit, and all three operators. For example, here's one incorrect
> solution:
>
>         123 + 45 - 67 - 89 = 100  (This is an incorrect formula; it totals 12)
>
> The quiz, then, is to solve this problem without thinking, instead letting the
> computer think for you. Your program should output every possible equation that
> can be formed, and the actual result of that equation. The equation that results
> in 100 should have stars around it. At the end, you should print out the number
> of formulae that were possible. Here's an excerpt of some example output:
>
>         ...
>         12 - 34 - 567 + 89 = -500
>         12 - 34 + 567 - 89 = 456
>         12 + 34 - 567 - 89 = -610
>         ************************
>         123 - 45 - 67 + 89 = 100
>         ************************
>         123456 - 7 - 8 + 9 = 123450
>         123456 - 7 + 8 - 9 = 123448
>         123456 + 7 - 8 - 9 = 123446
>         ...
>         168 possible equations tested
>
> You should not print the same equation more than once. ("1 - 2 - 3 + 456789" is
> the same as "1 - 2 - 3 + 456789", even if the computer thinks that the two minus
> symbols come in a different order.)
>
> Extra Credit: Write your program to accept an arbitrary number and ordering of
> digits, an arbitrary set of operators (but allowing the same operator more than
> once)

sorry for being picky but I guess it might be useful
- an arbitrary set of operators
+ an array of operators that can come in any order
hopefully somebody will find the correct formal expression to describe
the beast ...
, and an arbitrary target number that the equation is supposed to evaluate
> to.
>
>         [1] 2007 Puzzler Index: http://www.cartalk.com/content/puzzler/2007.html
>         [2] http://www.cartalk.com/content/puzzler/transcripts/200711/index.html
>
>
For the rest sounds like fun.

Cheers
Robert


-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw