NPR puzzle

[Alex Tweedly]

Charles Hartman wrote:

>
> On Jul 20, 2005, at 6:26 PM, Sarah Reichelt wrote:
>
>> You can either go through the word list and see if any match the  
>> elements, or you could go through the element list, making  
>> combinations and matching them to the words. I discarded this idea  
>> because the maths involved in working out all the permutations &  
>> combinations has long since flowed out of my brain, but I wonder if  
>> anyone else thought of using this method? Instinctively I feel it  
>> would take longer, but there are 3620 words and only 97 elements.
>
>
> If I remember right, that would be 97! / 5! x (97-5)!. And that -- if  
> I'm *also* getting the arithmetic right -- would mean 64,446,024 ten- 
> letter words to check. Looks like everyone's instinct to go the other  
> way was sound.
>
No, they're not "combinations" - there's nothing to say you can't use 
the same symbol more than once in a word (in fact, some of the words 
do), so the number of words to check is simply 97 ^ 5 = 8,587,340,257

Yes, I did think of doing it that way. I also, just for the heck of it 
thought of forming a monster regex
    "[Al|Ar|.....|Zr][Al| ...Zr]..."
and seeing what that did - but neither of them seemed very likely, so I 
didn't try them.

-- 
Alex Tweedly       http://www.tweedly.net



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