http://projecteuler.net/index.php?section=problems&id=54
カスタムのソートはsortByを使う。
import Data.List a = [ 3, 1, 4, 1, 5 ] b = sort a -- [1,1,3,4,5] c = zip [1..] a d = sortBy cmp c -- [(2,1),(4,1),(1,3),(3,4),(5,5)] cmp (n1,m1) (n2,m2) = compare m1 m2
compareは引数の大小に応じて、LT,EQ,GTの値を取る関数。
compare 1 2 -- LT compare 2 2 -- EQ compare 2 1 -- GT
sortByの第1引数も同様にLT,EQ,GTの値を取る関数を指定すればよい。
import Data.List index [] e = -1 index (x:xs) e = if x == e then 0 else if p == -1 then -1 else p + 1 where p = index xs e count [] e = 0 count (x:xs) e = (if x == e then 1 else 0) + (count xs e) card :: [Char] -> (Int,Char) card [s,t] = (index "23456789TJQKA" s, t) hands :: [Char] -> ([(Int,Char)],[(Int,Char)]) hands s = divide (map card (words s)) where divide [] = ([], []) divide (c:cs) | length (c:cs) > 5 = ([c] ++ a1, a2) | otherwise = (a1, [c] ++ a2) where (a1,a2) = divide cs collect nums = sortBy comp (f 12) where g (-1) = [] g n = (count nums n, n):(g (n - 1)) f n = filter (\(n,_) -> n > 0) (g n) comp (n1,m1) (n2,m2) = if n1 /= n2 then compare n2 n1 else compare m2 m1 comb_rank group = if group == [1,1,1,1,1] then 0 else if group == [2,1,1,1] then 1 else if group == [2,2,1] then 2 else if group == [3,1,1] then 3 else if group == [3,2] then 6 else if group == [4,1] then 7 else -1 rank :: [(Int,Char)] -> [Int] rank hand = (r nums suits):ds where (nums,suits) = unzip hand (group,ds) = unzip (collect nums) is_flush [s] = True is_flush (s:t:ss) = if s == t then is_flush (t:ss) else False is_straight [n] = True is_straight (n:m:ns) = if n == m + 1 then is_straight (m:ns) else False is_royal (n:ns) = n == 12 r nums suits = if (length group) == 5 then if is_flush suits then if is_straight ds then if is_royal ds then 9 else 8 else 5 else if is_straight ds then 4 else 0 else comb_rank group decide (h1,h2) = (compare (rank h1) (rank h2)) == GT main = do cs <- readFile "poker.txt" print (length (filter decide (map hands (lines cs))))
