finish v6

1 files changed, 13 insertions, 0 deletions

diff --git a/54a-60/55.hs b/54a-60/55.hs
new file mode 100644
index 0000000..5cc7b91
--- /dev/null
+++ b/54a-60/55.hs
@@ -0,0 +1,13 @@
+data Tree a = Empty | Branch a (Tree a) (Tree a) deriving (Show, Eq)
+
+cbalTree :: Int -> [Tree Char]
+
+cbalTree 0 = [Empty]
+cbalTree x
+  | even n = [Branch 'x' lt rt | let st = cbalTree ln, lt <- st, rt <- st]
+  | otherwise = let st1 = cbalTree ln
+                    st2 = cbalTree (n - ln) in
+                    [Branch 'x' lt rt | lt <- st1, rt <- st2] ++
+                    [Branch 'x' lt rt | lt <- st2, rt <- st1]
+    where ln = n `div` 2
+          n = x - 1