39 lines
894 B
Factor
39 lines
894 B
Factor
! Copyright (c) 2007 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 ;
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IN: project-euler.001
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! http://projecteuler.net/index.php?section=problems&id=1
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! DESCRIPTION
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! -----------
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! If we list all the natural numbers below 10 that are multiples of 3 or 5, we
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! get 3, 5, 6 and 9. The sum of these multiples is 23.
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! Find the sum of all the multiples of 3 or 5 below 1000.
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! SOLUTION
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! --------
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! Inclusion-exclusion principle
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: euler001 ( -- answer )
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0 999 3 <range> sum 0 999 5 <range> sum + 0 999 15 <range> sum - ;
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! [ euler001 ] 100 ave-time
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! 0 ms run / 0 ms GC ave time - 100 trials
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! ALTERNATE SOLUTIONS
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! -------------------
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: euler001a ( -- answer )
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1000 [ dup 5 mod swap 3 mod [ zero? ] either? ] subset sum ;
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! [ euler001a ] 100 ave-time
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! 0 ms run / 0 ms GC ave time - 100 trials
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MAIN: euler001
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