1 ! Copyright (c) 2007 Aaron Schaefer.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: kernel math math.ranges sequences ;
6 ! http://projecteuler.net/index.php?section=problems&id=1
11 ! If we list all the natural numbers below 10 that are multiples of 3 or 5, we
12 ! get 3, 5, 6 and 9. The sum of these multiples is 23.
14 ! Find the sum of all the multiples of 3 or 5 below 1000.
20 ! Inclusion-exclusion principle
24 : sum-divisible-by ( target n -- m )
25 [ /i dup 1+ * ] keep * 2 /i ;
29 : euler001 ( -- answer )
30 999 3 sum-divisible-by
31 999 5 sum-divisible-by +
32 999 15 sum-divisible-by - ;
34 ! [ euler001 ] 100 ave-time
35 ! 0 ms run / 0 ms GC ave time - 100 trials
41 : euler001a ( -- answer )
42 0 999 3 <range> sum 0 999 5 <range> sum + 0 999 15 <range> sum - ;
44 ! [ euler001a ] 100 ave-time
45 ! 0 ms run / 0 ms GC ave time - 100 trials
48 : euler001b ( -- answer )
49 1000 [ [ 5 mod ] [ 3 mod ] bi [ 0 = ] either? ] filter sum ;
51 ! [ euler001b ] 100 ave-time
52 ! 0 ms run / 0 ms GC ave time - 100 trials