1 files changed, 14 insertions, 0 deletions
diff --git a/61-69/69.hs b/61-69/69.hs
new file mode 100644
index 0000000..63c75b0
--- /dev/null
+++ b/61-69/69.hs
@@ -0,0 +1,14 @@
+data Tree a = Empty | Branch a (Tree a) (Tree a) deriving (Show, Eq)
+
+ds2tree :: [Char] -> Tree Char
+
+ds2tree l = fst $ build l
+    where build ('.':xs) = (Empty, xs)
+          build (x:xs) = (Branch x lt rt, xs'')
+            where (lt, xs') = build xs
+                  (rt, xs'') = build xs'
+
+tree2ds :: Tree Char -> [Char]
+
+tree2ds Empty = "."
+tree2ds (Branch x l r) = x:tree2ds l ++ tree2ds r