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Haskell 自習

-- 演習 2000-10-17 課題3

fill :: Int -> String -> String
fill num str
	| length str >= num = str
	| True = ' ' : fill (num - 1) str

fact :: Int -> Int
fact 0 = 1
fact n = n * fact(n - 1)

factArray = [ fact n | n <- [0 ..] ]

factTable :: Int -> String
factTable n = concat [factFill 2 20 n | n <- [0 .. n]] 
	where
		factFill :: Int -> Int -> Int -> String
		factFill n m x = (fill n (show x)) ++ (fill m (show(fact x))) ++ "\n"

-- 演習 2000-10-30

sumSquares m n
  = sqM + sqN
    where
    sqM = m * m
    sqN = n * n

addPairwise :: [Int] -> [Int] -> [Int]
addPairwise [] [] = []
addPairwise x [] = []
addPairwise [] y = []
addPairwise (x:xs) (y:ys) = (x + y):(addPairwise xs ys)

-- $$ は最後に計算した結果を表す

isOdd n
  | n <= 0    = False
  | otherwise = isEven (n-1)
   
isEven n
  | n < 0     = False
  | n == 0    = True
  | otherwise = isOdd (n-1)

-- 2000-10-30 課題1

maxOccursList :: [Int] -> (Int, Int)
maxOccursList x = (count (maximum x) x, maximum x)
	where
		count :: Int -> [Int] -> Int
		count n [] = 0
		count n (x:xs)  | n==x = (count n xs) + 1
						| True = count n xs
-- 2000-10-30 課題2

unique :: [Int] -> [Int]
unique xs = [x | x <- xs, count x xs == 1]
	where
		count n [] = 0
		count n (x:xs)  | n==x = (count n xs) + 1
						| True = count n xs

--2000-10-31 課題1

sublist :: Eq a => [a] -> [a] -> Bool
sublist [] _ = True
sublist _ [] = False
sublist (x:xs) (y:ys)
	| x == y = sublist xs ys
	| True = sublist (x:xs) ys

subseq :: Eq a => [a] -> [a] -> Bool
subseq [] _ = True
subseq (x:xs) (y:ys)
	| x == y = _subseq xs ys
	| True = _subseq (x:xs) ys
	where
		_subseq [] _ = True
		_subseq (x:xs) (y:ys)
			| x == y = _subseq xs ys
			| True = False
--2000-11-17 演習

--1. 整数のリストを引数とする，次の関数を定義せよ（mapまたはfilterを使うこと）．
--a) 各要素の二乗のリストを返す関数．
doubleList :: [Int] -> [Int]
doubleList xs = map (2 *) xs

--b) 全ての要素が0より大きい場合にTrueを，そうでない場合にFalseを返す関数．


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