! Copyright (c) 2008 Aaron Schaefer.
! See http://factorcode.org/license.txt for BSD license.
-USING: kernel math math.functions math.ranges math.order
-project-euler.common sequences layouts ;
+USING: kernel math ranges math.order project-euler.common
+sequences layouts ;
IN: project-euler.044
! http://projecteuler.net/index.php?section=problems&id=44
dup 3 * 1 - * 2 /i ; inline
: sum-and-diff? ( m n -- ? )
- [ + ] [ - ] 2bi [ pentagonal? ] bi@ and ; inline
+ [ + ] [ - ] 2bi [ pentagonal? ] both? ; inline
: euler044-step ( min m n -- min' )
[ nth-pentagonal ] bi@
PRIVATE>
: euler044 ( -- answer )
- most-positive-fixnum >fixnum
- 2500 [1,b] [
- dup [1,b] [
+ most-positive-fixnum
+ 2500 [1..b] [
+ dup [1..b] [
euler044-step
] with each
] each ;