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