! Copyright (c) 2008 Aaron Schaefer.
! See http://factorcode.org/license.txt for BSD license.
-USING: ascii io.files kernel math math.functions namespaces make
- project-euler.common sequences sequences.lib splitting io.encodings.ascii ;
+USING: ascii io.encodings.ascii io.files kernel make math math.functions
+project-euler.common sequences splitting ;
IN: project-euler.042
! http://projecteuler.net/index.php?section=problems&id=42
: (triangle-upto) ( limit n -- )
2dup nth-triangle > [
- dup nth-triangle , 1+ (triangle-upto)
+ dup nth-triangle , 1 + (triangle-upto)
] [
2drop
] if ;
triangle-upto [ member? ] curry count ;
! [ euler042 ] 100 ave-time
-! 27 ms run / 1 ms GC ave time - 100 trials
+! 19 ms ave run time - 1.97 SD (100 trials)
! ALTERNATE SOLUTIONS
<PRIVATE
: triangle? ( n -- ? )
- 8 * 1+ sqrt 1- 2 / 1 mod zero? ;
+ 8 * 1 + sqrt 1 - 2 / 1 mod zero? ;
PRIVATE>
source-042 [ alpha-value ] map [ triangle? ] count ;
! [ euler042a ] 100 ave-time
-! 25 ms run / 1 ms GC ave time - 100 trials
+! 21 ms ave run time - 2.2 SD (100 trials)
-MAIN: euler042a
+SOLUTION: euler042a