1 files changed, 10 insertions, 0 deletions
diff --git a/11-20/13.hs b/11-20/13.hs
new file mode 100644
index 0000000..db5509e
--- /dev/null
+++ b/11-20/13.hs
@@ -0,0 +1,10 @@
+data ListItem a = Single a | Multiple Int a deriving Show
+encodeDirect :: Eq a => [a] -> [ListItem a]
+
+encodeDirect [] = []
+encodeDirect [x] = [Single x]
+encodeDirect (x:xs) = if x == h then n:ys else (Single x):(y:ys)
+    where (y:ys) = encodeDirect xs
+          helper (Single z) = (Multiple 2 z, z)
+          helper (Multiple c z) = (Multiple (c + 1) z, z)
+          (n, h) = helper y