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-- https://www.codewars.com/kata/521c2db8ddc89b9b7a0000c1
module Snail where
snail :: [[Int]] -> [Int]
snail [] = []
snail arr = foldl1 (++) $ map (roundAt w h arr) [0..center]
where
w = length (arr !! 0)
h = length arr
center = min (w `div` 2) (h `div` 2)
rowRange col from to arr =
drop from $ take (to+1) $ arr !! col
colRange row from to arr =
map (!!row) $ drop from $ take (to+1) arr
roundAt w h arr x =
(rowRange x x (w-x-1) arr) ++
(colRange (w-x-1) (x+1) (h-x-1) arr) ++
(reverse $ rowRange (h-x-1) x (w-x-2) arr) ++
(reverse $ colRange x (x+1) (h-x-2) arr)
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