28 lines
831 B
Text
28 lines
831 B
Text
:import std/Combinator .
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:import std/Number .
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:import std/List .
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merge y [[[∅?1 0 (1 [[2 [[go]]]])]]]
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go 3 <? 1 (3 : (6 2 4)) (1 : (6 5 0))
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# classic version while avoiding duplicate generation
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hammings-classic (+1) : (foldr u empty ((+2) : ((+3) : {}(+5))))
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u [[y [merge 1 ((mul 2) <$> ((+1) : 0))]]]
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:test ((hammings-classic !! (+42)) =? (+162)) ([[1]])
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# enumeration by a chain of folded merges (faster)
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hammings-folded ([(0 ∘ a) ∘ (0 ∘ b)] (foldr merge1 empty)) $ c
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merge1 [[1 [[1 : (merge 0 2)]]]]
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a iterate (map (mul (+5)))
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b iterate (map (mul (+3)))
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c iterate (mul (+2)) (+1)
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:test ((hammings-folded !! (+42)) =? (+162)) ([[1]])
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# --- output ---
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main [first-twenty : (n1691 : {}n1000000)]
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first-twenty take (+20) hammings-folded
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n1691 hammings-folded !! (+1690)
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n1000000 hammings-folded !! (+999999)
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