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1 files changed, 23 insertions, 0 deletions

diff --git a/4-kyu/snail.hs b/4-kyu/snail.hs
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+++ b/4-kyu/snail.hs
@@ -0,0 +1,23 @@
+-- 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)