in reply to Re^4: Brute force vs algorithm (PWC # 100)
in thread Brute force vs algorithm (PWC # 100)

> And when one doesn't do it right, one will just end-up visiting each cell anyway.

And I think there is no algorithm which can guaranty otherwise.

consider this input

2 2 2 2 2 2 2 2 2 2 . . . . . 2s in between 2 2 . . 2 1 last row

no matter which top-down search you apply, you can move the 1 in a way that it's only found at last try.

Which means all cells needed to be visited.°

update

°) NB: complexity big O() calculations are about worst case (if not stated otherwise )

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery