Minor tweak to project-euler
parent
53c8299576
commit
625d4037fe
|
@ -1,15 +1,21 @@
|
|||
! Copyright (c) 2008 Eric Mertens
|
||||
! See http://factorcode.org/license.txt for BSD license.
|
||||
USING: kernel math sequences locals ;
|
||||
USING: kernel math sequences sequences.private locals hints ;
|
||||
IN: project-euler.150
|
||||
|
||||
<PRIVATE
|
||||
|
||||
! sequence helper functions
|
||||
|
||||
: partial-sums ( seq -- seq )
|
||||
: partial-sums ( seq -- sums )
|
||||
0 [ + ] accumulate swap suffix ; inline
|
||||
|
||||
: (partial-sum-infimum) ( inf sum elt -- inf sum )
|
||||
+ [ min ] keep ; inline
|
||||
|
||||
: partial-sum-infimum ( seq -- seq )
|
||||
0 0 rot [ (partial-sum-infimum) ] each drop ; inline
|
||||
|
||||
: generate ( n quot -- seq )
|
||||
[ drop ] swap compose map ; inline
|
||||
|
||||
|
@ -20,25 +26,27 @@ IN: project-euler.150
|
|||
! triangle generator functions
|
||||
|
||||
: next ( t -- new-t s )
|
||||
615949 * 797807 + 1 20 shift mod dup 1 19 shift - ; inline
|
||||
615949 * 797807 + 20 2^ rem dup 19 2^ - ; inline
|
||||
|
||||
: sums-triangle ( -- seq )
|
||||
0 1000 [ 1+ [ next ] generate partial-sums ] map nip ;
|
||||
0 1000 [ 1+ [ next ] generate partial-sums ] map nip ;
|
||||
|
||||
PRIVATE>
|
||||
PRIVATE> USING: arrays kernel.private ;
|
||||
|
||||
:: (euler150) ( m -- n )
|
||||
[let | table [ sums-triangle ] |
|
||||
m [| x |
|
||||
x 1+ [| y |
|
||||
m x - [| z |
|
||||
x z + table nth
|
||||
[ y z + 1+ swap nth ]
|
||||
[ y swap nth ] bi -
|
||||
] map partial-sums infimum
|
||||
x z + table nth-unsafe
|
||||
[ y z + 1+ swap nth-unsafe ]
|
||||
[ y swap nth-unsafe ] bi -
|
||||
] map partial-sum-infimum
|
||||
] map-infimum
|
||||
] map-infimum
|
||||
] ;
|
||||
|
||||
HINTS: (euler150) fixnum ;
|
||||
|
||||
: euler150 ( -- n )
|
||||
1000 (euler150) ;
|
||||
|
|
Loading…
Reference in New Issue