Slava Pestov 2008-04-21 01:38:47 -05:00
commit bc95aa8585
2 changed files with 28 additions and 0 deletions

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@ -0,0 +1,24 @@
! Copyright (c) 2008 Eric Mertens
! See http://factorcode.org/license.txt for BSD license.
USING: kernel math math.functions sequences sequences.lib ;
IN: project-euler.148
<PRIVATE
: sum-1toN ( n -- sum )
dup 1+ * 2/ ; inline
: >base7 ( x -- y )
[ dup 0 > ] [ 7 /mod ] [ ] unfold nip ;
: (use-digit) ( prev x index -- next )
[ [ 1+ * ] [ sum-1toN 7 sum-1toN ] bi ] dip ^ * + ;
PRIVATE>
: (euler148) ( x -- y )
>base7 0 [ (use-digit) ] reduce-index ;
: euler148 ( -- y )
10 9 ^ (euler148) ;

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@ -35,6 +35,10 @@ MACRO: firstn ( n -- )
#! quot: ( elt index -- obj )
prepare-index 2map ; inline
: reduce-index ( seq identity quot -- )
#! quot: ( prev elt index -- next )
swapd each-index ; inline
! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
: each-percent ( seq quot -- )