Cleaning up source a bit

1 files changed, 33 insertions, 0 deletions

diff --git a/sort/pancake.hs b/sort/pancake.hs
new file mode 100644
index 0000000..2bfdb4a
--- /dev/null
+++ b/sort/pancake.hs
@@ -0,0 +1,33 @@
+module Pancake (
+    pancakeSort
+    ) where
+
+
+
+pancakeSort :: Ord a => [a] -> [a]
+pancakeSort [] = []
+pancakeSort cakeStack =
+    let selectedCake = indexOfLargest cakeStack
+        cakeStack' = (doFlip (length cakeStack)) . (doFlip selectedCake) $ cakeStack
+    in (pancakeSort (init cakeStack')) ++ [last cakeStack']
+
+
+
+indexOfLargest :: Ord a => [a] -> Int
+indexOfLargest (x:xs) =
+    let f m i j y = if length y == 0
+                        then i
+                        else if (head y) > m
+                                then f (head y) j (j+1) (tail y)
+                                else f m i (j+1) (tail y)
+    in f x 0 1 xs
+
+
+
+doFlip :: Int -> [a] -> [a]
+doFlip depth list =
+    let prefix = take (depth + 1) list
+        rest = drop (depth + 1) list
+    in (reverse prefix) ++ rest
+
+