split :: (Eq a) => a -> [a] -> [[a]] split _ [] = [] split delimiter xs = left : (split delimiter right') where (left, right) = break (== delimiter) xs right' = if null right then [] else tail right p22 = do fh <- openFile "names.txt" Read…

combinations :: [a] -> [[a]] combinations [] = [[]] combinations (x:xs) = concat [[t, (x:t)] | t <- combinations xs] amicable a limit = a /= d(a) && d(a) < limit && a == d(d(a)) d a = (sum $ unique $ sort $ map product $ combinations $ fac…

sum $ map (\x -> read [x]::Int) $ show $ product [1..100]

ツェラーの公式を使った p19_z :: Int -> Int -> Int -> Int p19_z year month day | month < 3 = p19_z (year-1) (month+12) day | otherwise = mod (year + (div year 4) - (div year 100) + (div year 400) + (div (13 * month + 8) 5) + day) 7 length […

最小公倍数を求める lcm があったのでスッキリ書き直した foldr lcm 1 [1..20]

factor3 :: Integral a => a -> [a] factor3 n = unique $ sort $ first ++ second where first = [x | x <- [1..limit], n `mod` x == 0] second = map (\x -> div n x) first limit = truncate $ sqrt $ fromIntegral n p23 n = p23' [1..n] $ gen_ab_list…

take 10 $ show $ sum $ map (\x -> read x::Integer) $ lines p13_input

uniqueCount :: (Eq a) => [a] -> [(a,Int)] uniqueCount [] = [] uniqueCount [x] = [(x,1)] uniqueCount all@(x:xs) = (x, length left) : uniqueCount right where (left, right) = break (\a -> a /= x) all product $ map (\x -> product (replicate (f…

Problem18と同じプログラムで解けるので。 p67 = do fh <- openFile "triangle.txt" ReadMode c <- hGetContents fh let triangle = map (\line -> map (\s -> read s::Integer) $ words line) $ lines c putStr $ show $ maximum $ p18 triangle

p18_input = "75\n95 64\n17 47 82\n18 35 87 10\n20 04 82 47 65\n19 01 23 75 03 34\n88 02 77 73 07 63 67\n99 65 04 28 06 16 70 92\n41 41 26 56 83 40 80 70 33\n41 48 72 33 47 32 37 16 94 29\n53 71 44 65 25 43 91 52 97 51 14\n70 11 33 28 77 73…

p17_n_to_word :: Int -> String p17_n_to_word 0 = "" p17_n_to_word 1 = "one" p17_n_to_word 2 = "two" p17_n_to_word 3 = "three" p17_n_to_word 4 = "four" p17_n_to_word 5 = "five" p17_n_to_word 6 = "six" p17_n_to_word 7 = "seven" p17_n_to_word…

sum $ map (\x -> read [x]::Int) $ show $ product $ replicate 1000 2

p15 :: Integer -> Integer -> Integer p15 w h = product [1..(w+h)] `div` product [1..w] `div` product [1..h] p15 20 20

ものすごい時間がかかる... いつか書き直す p14 :: (Integer, Integer) -> [Integer] -> (Integer, Integer) p14 max' [] = max' p14 max' (x:xs) = p14 new_max xs where ret = p14' x new_max = if (fst max') < (fst ret) then ret else max' p14' :: Int…

計算量とか最適化とかは考えずとりあえず解いてみる

かなりグダグダになった... Haskellがうまくあやつれるようになったら書き直す p11_input = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08\n49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00\n81 49 31 73 55 79 14 29 93 71 …

sum $ prime 2000000

p9 :: [[Int]] -> [[Int]] p9 [] = [] p9 (x:xs) | ok x = x : p9 xs | otherwise = p9 xs where ok (a:b:c:_) | a*a + b*b == c*c && a+b+c == 1000 = True | otherwise = False (\x -> head x * (head $ tail x) * (head $ tail $ tail x )) $ head $ p9 […

split_s_to_i :: [Char] -> [Int] split_s_to_i [] = [] split_s_to_i (x:xs) = (read [x]::Int) : (split_s_to_i xs) p8 :: [Int] -> [Int] p8 (a:b:c:d:e:xs) = a*b*c*d*e : p8 (b:c:d:e:xs) p8 _ = [] maxiumu $ p8 $ split_s_to_i "7316....."

10001番目の判定をサボったので100000と1000000の2回やって値が同じなので正解と判定 last $ take 10001 $ prime 100000 last $ take 10001 $ prime 1000000

((\x->x*x) $ sum [1..100]) - (sum $ map (\x->x*x) [1..100])

p5 :: [Integer] -> Integer p5 s = _p5 1 s where _p5 r [] = r _p5 r (x:xs) = _p5 ( r * (foldl (*) 1 (_sub (factor x) (factor r)))) xs _sub left [] = left _sub [] right = [] _sub (l:ls) (r:rs) | l == r = _sub ls rs | l < r = l : _sub ls (r:r…

maximum $ filter (\n -> (reverse $ show n) == (show n)) $ map (\pair -> fst pair * snd pair) [(x,y) | x <- [1..999], y <- [1..999]]

prime :: Integer -> [Integer] prime m = 2 : era [3,5..m] where era [] = [] era (p:xs) | p*p > m = p : xs | otherwise = p : era [x | x<-xs, x `mod` p /= 0] factor :: Integer -> [Integer] factor x = _factor x $ prime x where _factor 1 _ = []…

fib :: [Int] fib = 1 : 2 : zipWith (+) fib (tail fib) sum $ filter even $ takeWhile (\x -> x < 4000000) $ fib

sum $ filter (\x -> x `mod` 3 == 0 || x `mod` 5 == 0) [1..999]