Beefy Boxes and Bandwidth Generously Provided by pair Networks
The stupid question is the question not asked

Re^3: Puzzle Time

by LanX (Chancellor)
on Dec 23, 2012 at 15:25 UTC ( #1010106=note: print w/ replies, xml ) Need Help??

in reply to Re^2: Puzzle Time
in thread Puzzle Time

> Allow me one nit-pick:

Yeah I noticed this, but was too tired to correct it. =)

Anyway my guess was wrong (9!+8!+7!+...) you got it right.

> (way faster than my brute force approach).

If it's about speed you can limit the $maxlevel, because the longest number can't have more than 7 digits:

  1. Evidently 0 is excluded!

  2. Any number this long includes even ciphers. So 5 is excluded! But any number divisible by 5 and 2 must end with a 0

  3. An number from the remaining 8 digits would include 9 and 3, but the digit sum would be 40, which is impossible.╣

Even your approach with a brute force loop could compete when only considering 7 digits, cause you don't have the overhead of 1 million function calls.

Cheers Rolf

╣) and therefor a 7 digit number excludes 4 to be divisible by 9.

Comment on Re^3: Puzzle Time

Log In?

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://1010106]
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others studying the Monastery: (6)
As of 2016-05-30 16:47 GMT
Find Nodes?
    Voting Booth?