143 lines
3.3 KiB
AppleScript
143 lines
3.3 KiB
AppleScript
-- josephusSurvivor :: Int -> Int -> Int
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on josephusSurvivor(n, k)
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script go
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on |λ|(x, a)
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(k + x) mod a
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end |λ|
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end script
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foldl(go, 0, enumFromTo(1, n))
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end josephusSurvivor
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-- josephusSequence :: Int -> Int -> [Int]
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on josephusSequence(n, k)
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script josephus
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on |λ|(m, xs)
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if 0 ≠ m then
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set {l, r} to splitAt((k - 1) mod m, xs)
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{item 1 of r} & |λ|(m - 1, rest of r & l)
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else
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{}
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end if
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end |λ|
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end script
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|λ|(n, enumFromTo(0, n - 1)) of josephus
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end josephusSequence
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--------------------------- TEST ---------------------------
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on run
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unlines({"Josephus survivor -> " & str(josephusSurvivor(41, 3)), ¬
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"Josephus sequence ->" & linefeed & tab & ¬
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showList(josephusSequence(41, 3))})
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end run
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---------------- REUSABLE GENERIC FUNCTIONS ----------------
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-- enumFromTo :: Int -> Int -> [Int]
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on enumFromTo(m, n)
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if m ≤ n then
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set lst to {}
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repeat with i from m to n
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set end of lst to i
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end repeat
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lst
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else
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{}
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end if
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end enumFromTo
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-- foldl :: (a -> b -> a) -> a -> [b] -> a
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on foldl(f, startValue, xs)
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tell mReturn(f)
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set v to startValue
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set lng to length of xs
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repeat with i from 1 to lng
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set v to |λ|(v, item i of xs, i, xs)
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end repeat
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return v
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end tell
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end foldl
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-- map :: (a -> b) -> [a] -> [b]
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on map(f, xs)
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-- The list obtained by applying f
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-- to each element of xs.
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tell mReturn(f)
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set lng to length of xs
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set lst to {}
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repeat with i from 1 to lng
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set end of lst to |λ|(item i of xs, i, xs)
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end repeat
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return lst
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end tell
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end map
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-- mReturn :: First-class m => (a -> b) -> m (a -> b)
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on mReturn(f)
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-- 2nd class handler function lifted into 1st class script wrapper.
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if script is class of f then
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f
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else
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script
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property |λ| : f
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end script
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end if
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end mReturn
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-- intercalate :: String -> [String] -> String
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on intercalate(delim, xs)
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set {dlm, my text item delimiters} to ¬
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{my text item delimiters, delim}
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set str to xs as text
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set my text item delimiters to dlm
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str
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end intercalate
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-- showList :: [a] -> String
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on showList(xs)
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script show
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on |λ|(x)
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x as text
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end |λ|
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end script
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"[" & intercalate(",", map(show, xs)) & "]"
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end showList
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-- splitAt :: Int -> [a] -> ([a], [a])
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on splitAt(n, xs)
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if n > 0 and n < length of xs then
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if class of xs is text then
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{items 1 thru n of xs as text, ¬
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items (n + 1) thru -1 of xs as text}
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else
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{items 1 thru n of xs, items (n + 1) thru -1 of xs}
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end if
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else
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if n < 1 then
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{{}, xs}
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else
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{xs, {}}
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end if
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end if
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end splitAt
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-- str :: a -> String
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on str(x)
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x as string
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end str
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-- unlines :: [String] -> String
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on unlines(xs)
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-- A single string formed by the intercalation
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-- of a list of strings with the newline character.
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set {dlm, my text item delimiters} to ¬
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{my text item delimiters, linefeed}
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set str to xs as text
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set my text item delimiters to dlm
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str
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end unlines
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