19 lines
574 B
APL
19 lines
574 B
APL
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⍝ recursive dfn:
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dfnHailstone←{
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c←⊃⌽⍵ ⍝ last element
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1=c:1 ⍝ if it is 1, stop.
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⍵,∇(1+2|c)⊃(c÷2)(1+3×c) ⍝ otherwise pick the next step, and append the result of the recursive call
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}
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⍝ tradfn version:
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∇seq←hailstone n;next
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⍝ Returns the hailstone sequence for a given number
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seq←n ⍝ Init the sequence
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:While n≠1
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next←(n÷2) (1+3×n) ⍝ Compute both possibilities
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n←next[1+2|n] ⍝ Pick the appropriate next step
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seq,←n ⍝ Append that to the sequence
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:EndWhile
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∇
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