1 ! Copyright (c) 2008 Eric Mertens
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: sequences combinators kernel sequences.lib math math.order
9 : (pick-sheet) ( seq i -- newseq )
21 : pick-sheet ( seq i -- res )
22 2dup swap nth dup zero? [
25 [ (pick-sheet) (euler151) ] dip *
28 : (euler151) ( x -- y )
31 { { 0 0 1 0 } [ { 0 0 0 1 } (euler151) 1+ ] }
32 { { 0 1 0 0 } [ { 0 0 1 1 } (euler151) 1+ ] }
33 { { 1 0 0 0 } [ { 0 1 1 1 } (euler151) 1+ ] }
34 [ [ dup length [ pick-sheet ] with map sum ] [ sum ] bi / ]
40 { 1 1 1 1 } (euler151)