35 lines
975 B
Factor
35 lines
975 B
Factor
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! Copyright (C) 2020 Bubbler.
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! See http://factorcode.org/license.txt for BSD license.
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USING: arrays grouping kernel locals math math.bits
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math.functions math.polynomials prettyprint sequences ;
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IN: projecteuler.euler258
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: p-sq' ( poly -- poly' )
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64 2^ swap polyval sq make-bits 64 group [ bits>number ] map ;
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:: polykm ( poly k m -- poly' )
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poly length 2 - k >= [ k 0 <array> 1 suffix ] [
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poly k 2/ m polykm
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p-sq' k odd? [ 0 prefix ] when
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poly p/mod nip [ m mod ] map
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] if ;
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:: polykm-special ( n k m -- poly )
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n 1 - k >= [ k 0 <array> 1 suffix ] [
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n k 2/ m polykm-special
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p-sq' k odd? [ 0 prefix ] when
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2 [ n short cut dup 0 prefix p+ p+ ] times [ m mod ] map
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] if ;
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: euler258-slow ( n k m -- ans )
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[ 2 - 0 <array> { -1 -1 } { 1 } surround ] 2dip
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[ polykm sum ] keep mod ;
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: euler258-fast ( n k m -- ans )
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[ polykm-special sum ] keep mod ;
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: euler258-main ( -- )
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2000 10 18 ^ 20092010 euler258-fast . ;
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MAIN: euler258-main
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