33 lines
914 B
Factor
33 lines
914 B
Factor
! Copyright (c) 2008 Aaron Schaefer.
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! See http://factorcode.org/license.txt for BSD license.
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USING: kernel math.functions math.ranges project-euler.common
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sequences math.order ;
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IN: project-euler.056
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! http://projecteuler.net/index.php?section=problems&id=56
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! DESCRIPTION
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! -----------
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! A googol (10^100) is a massive number: one followed by one-hundred zeros;
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! 100^100 is almost unimaginably large: one followed by two-hundred zeros.
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! Despite their size, the sum of the digits in each number is only 1.
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! Considering natural numbers of the form, a^b, where a, b < 100, what is the
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! maximum digital sum?
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! SOLUTION
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! --------
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! Through analysis, you only need to check when a and b > 90
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: euler056 ( -- answer )
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90 100 [a,b) dup cartesian-product
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[ first2 ^ number>digits sum ] [ max ] map-reduce ;
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! [ euler056 ] 100 ave-time
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! 22 ms ave run time - 2.13 SD (100 trials)
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SOLUTION: euler056
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