44 lines
1.0 KiB
Factor
44 lines
1.0 KiB
Factor
! Copyright (c) 2007, 2008 Aaron Schaefer.
|
|
! See http://factorcode.org/license.txt for BSD license.
|
|
USING: kernel math math.ranges sequences project-euler.common ;
|
|
IN: project-euler.006
|
|
|
|
! http://projecteuler.net/index.php?section=problems&id=6
|
|
|
|
! DESCRIPTION
|
|
! -----------
|
|
|
|
! The sum of the squares of the first ten natural numbers is,
|
|
! 1² + 2² + ... + 10² = 385
|
|
|
|
! The square of the sum of the first ten natural numbers is,
|
|
! (1 + 2 + ... + 10)² = 55² = 3025
|
|
|
|
! Hence the difference between the sum of the squares of the first ten natural
|
|
! numbers and the square of the sum is 3025 - 385 = 2640.
|
|
|
|
! Find the difference between the sum of the squares of the first one hundred
|
|
! natural numbers and the square of the sum.
|
|
|
|
|
|
! SOLUTION
|
|
! --------
|
|
|
|
<PRIVATE
|
|
|
|
: sum-of-squares ( seq -- n )
|
|
0 [ sq + ] reduce ;
|
|
|
|
: square-of-sum ( seq -- n )
|
|
sum sq ;
|
|
|
|
PRIVATE>
|
|
|
|
: euler006 ( -- answer )
|
|
100 [1,b] [ sum-of-squares ] [ square-of-sum ] bi - abs ;
|
|
|
|
! [ euler006 ] 100 ave-time
|
|
! 0 ms ave run time - 0.24 SD (100 trials)
|
|
|
|
SOLUTION: euler006
|