Alternate solution to Project Euler problem 2

extra/project-euler/002/002.factor

@@ -1,6 +1,6 @@
 ! Copyright (c) 2007 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel math sequences ;
+USING: kernel math sequences shuffle ;
 IN: project-euler.002
 
 ! http://projecteuler.net/index.php?section=problems&id=2
@@ -35,4 +35,18 @@ PRIVATE>
 ! [ euler002 ] 100 ave-time
 ! 0 ms run / 0 ms GC ave time - 100 trials
 
-MAIN: euler002
+
+! ALTERNATE SOLUTIONS
+! -------------------
+
+: fib-upto* ( n -- seq )
+    0 1 [ pick over >= ] [ tuck + dup ] [ ] unfold 3nip
+    1 head-slice* { 0 1 } swap append ;
+
+: euler002a ( -- answer )
+    1000000 fib-upto* [ even? ] subset sum ;
+
+! [ euler002a ] 100 ave-time
+! 0 ms run / 0 ms GC ave time - 100 trials
+
+MAIN: euler002a