use reject instead of [ ... not ] filter.

[factor.git] / extra / project-euler / 004 / 004.factor

diff --git a/extra/project-euler/004/004.factor b/extra/project-euler/004/004.factor
index 1f268f15001743ed1488d018b69affa130b4707a..dbbeb704379e476b7d22f645e47bbc9d0ac1f949 100644 (file)
--- a/extra/project-euler/004/004.factor
+++ b/extra/project-euler/004/004.factor
@@ -1,7 +1,7 @@
 ! Copyright (c) 2007 Aaron Schaefer, Daniel Ehrenberg.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: hashtables kernel math math.ranges project-euler.common sequences
-    sorting sets ;
+USING: hashtables kernel math math.functions math.ranges project-euler.common
+    sequences sorting sets ;
 IN: project-euler.004
 
 ! http://projecteuler.net/index.php?section=problems&id=4
@@ -21,7 +21,7 @@ IN: project-euler.004
 <PRIVATE
 
 : source-004 ( -- seq )
-    100 999 [a,b] [ 10 mod zero? not ] filter ;
+    100 999 [a,b] [ 10 divisor? ] reject ;
 
 : max-palindrome ( seq -- palindrome )
     natural-sort [ palindrome? ] find-last nip ;
@@ -29,9 +29,9 @@ IN: project-euler.004
 PRIVATE>
 
 : euler004 ( -- answer )
-    source-004 dup cartesian-product [ product ] map prune max-palindrome ;
+    source-004 dup [ * ] cartesian-map combine max-palindrome ;
 
 ! [ euler004 ] 100 ave-time
-! 1608 ms run / 102 ms GC ave time - 100 trials
+! 1164 ms ave run time - 39.35 SD (100 trials)
 
-MAIN: euler004
+SOLUTION: euler004