55 lines
1.1 KiB
Factor
55 lines
1.1 KiB
Factor
! Copyright (c) 2007 Aaron Schaefer.
|
|
! See http://factorcode.org/license.txt for BSD license.
|
|
USING: kernel math math.ranges sequences ;
|
|
IN: project-euler.001
|
|
|
|
! http://projecteuler.net/index.php?section=problems&id=1
|
|
|
|
! DESCRIPTION
|
|
! -----------
|
|
|
|
! If we list all the natural numbers below 10 that are multiples of 3 or 5, we
|
|
! get 3, 5, 6 and 9. The sum of these multiples is 23.
|
|
|
|
! Find the sum of all the multiples of 3 or 5 below 1000.
|
|
|
|
|
|
! SOLUTION
|
|
! --------
|
|
|
|
! Inclusion-exclusion principle
|
|
|
|
<PRIVATE
|
|
|
|
: sum-divisible-by ( target n -- m )
|
|
[ /i dup 1+ * ] keep * 2 /i ;
|
|
|
|
PRIVATE>
|
|
|
|
: euler001 ( -- answer )
|
|
999 3 sum-divisible-by
|
|
999 5 sum-divisible-by +
|
|
999 15 sum-divisible-by - ;
|
|
|
|
! [ euler001 ] 100 ave-time
|
|
! 0 ms run / 0 ms GC ave time - 100 trials
|
|
|
|
|
|
! ALTERNATE SOLUTIONS
|
|
! -------------------
|
|
|
|
: euler001a ( -- answer )
|
|
0 999 3 <range> sum 0 999 5 <range> sum + 0 999 15 <range> sum - ;
|
|
|
|
! [ euler001a ] 100 ave-time
|
|
! 0 ms run / 0 ms GC ave time - 100 trials
|
|
|
|
|
|
: euler001b ( -- answer )
|
|
1000 [ [ 5 mod ] [ 3 mod ] bi [ 0 = ] either? ] filter sum ;
|
|
|
|
! [ euler001b ] 100 ave-time
|
|
! 0 ms run / 0 ms GC ave time - 100 trials
|
|
|
|
MAIN: euler001
|