[Haskell-cafe] Josephus problem and style
ross at soi.city.ac.uk
Sun Apr 1 19:41:46 EDT 2007
On Mon, Apr 02, 2007 at 09:12:17AM +1000, Duncan Coutts wrote:
> On Sun, 2007-04-01 at 16:46 -0400, Paul Hudak wrote:
> > Here's a solution that I think is a bit more elegant.
> > -Paul
> > josephus n k =
> > let loop xs = let d:r = drop (k-1) xs
> > in d : loop (filter (/= d) r)
> > in take n (loop (cycle [1..n]))
> .. must.. resist ... urge to fuse ...
Resist -- there's little to gain from fusing an asymptotically slower
algorithm. (This is O(n^2) compared with the original O(nk) and a
possible O(n log k).)
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