42 lines
1.3 KiB
Haskell
42 lines
1.3 KiB
Haskell
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fib :: Int -> Int
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fib 0 = 0
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fib 1 = 1
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fib n = fib (n-2) + fib (n-1)
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primeTest :: Int -> Int -> Bool
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primeTest _ 1 = True
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primeTest x y | (rem x y == 0) = False
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| otherwise = primeTest x (y-1)
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prime :: Int -> Bool
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prime x = primeTest x (x-1)
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powersOfTwo :: Int -> Int -> [Int]
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powersOfTwo a b | a > b = []
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| otherwise = (2^a) : (powersOfTwo (a+1) b)
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contains :: Int -> [Int] -> Bool
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contains _ [] = False
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contains x (y:ys) | x == y = True
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| otherwise = contains x ys
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intersection :: [Int] -> [Int] -> [Int]
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intersection [] _ = []
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intersection (x:xs) ys | contains x ys = x:(intersection xs ys)
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| otherwise = intersection xs ys
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selectSmallest :: [Int] -> Int -> Int
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selectSmallest [] y = y
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selectSmallest (x:xs) y | x < y = selectSmallest xs x
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| otherwise = selectSmallest xs y
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removeFirst :: [Int] -> Int -> Bool -> [Int]
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removeFirst [] _ _ = []
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removeFirst xs _ True = xs
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removeFirst (x:xs) y False | x == y = removeFirst xs y True
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| otherwise = x:(removeFirst xs y False)
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selectKsmallest :: Int -> [Int] -> Int
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selectKsmallest 1 (x:xs) = selectSmallest xs x
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selectKsmallest k (x:xs) = selectKsmallest (k-1) (removeFirst (x:xs) (selectSmallest xs x) False)
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