40 lines
1.0 KiB
Factor
40 lines
1.0 KiB
Factor
|
! Copyright (c) 2007 Aaron Schaefer.
|
||
|
|
! See http://factorcode.org/license.txt for BSD license.
|
||
|
|
USING: kernel math math.functions math.ranges sequences ;
|
||
|
|
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
|
||
|
|
! --------
|
||
|
|
|
||
|
|
: sum-of-squares ( seq -- n )
|
||
|
|
0 [ sq + ] reduce ;
|
||
|
|
|
||
|
|
: square-of-sums ( seq -- n )
|
||
|
|
0 [ + ] reduce sq ;
|
||
|
|
|
||
|
|
: euler006 ( -- answer )
|
||
|
|
1 100 [a,b] dup sum-of-squares swap square-of-sums - abs ;
|
||
|
|
|
||
|
|
! [ euler006 ] 100 ave-time
|
||
|
|
! 0 ms run / 0 ms GC ave time - 100 trials
|
||
|
|
|
||
|
|
MAIN: euler006
|