From 84e6753005e57827c78b50ad0a26ffa0d0da55e4 Mon Sep 17 00:00:00 2001
From: Joe Zhao <ztuowen@gmail.com>
Date: Mon, 6 Apr 2015 13:53:37 +0800
Subject: +59 +60

---
 H59.hs | 13 +++++++++++++
 H60.hs | 18 ++++++++++++++++++
 2 files changed, 31 insertions(+)
 create mode 100644 H59.hs
 create mode 100644 H60.hs

diff --git a/H59.hs b/H59.hs
new file mode 100644
index 0000000..3d44ac3
--- /dev/null
+++ b/H59.hs
@@ -0,0 +1,13 @@
+module H59 where
+
+import Tree
+
+hbalTree :: Int -> [Tree Char]
+hbalTree 0 = [Empty]
+hbalTree h = [Branch 'x' x y | let tl = concatMap hbalTree $ filter (>=0) [h-2,h-1],x <- tl, y <- tl]
+
+hbalTree' 1 = [Branch 'x' Empty Empty]
+hbalTree' h = hbalhelper (h-1) [Branch 'x' Empty Empty] [Empty]
+    where 
+        hbalhelper 0 x _ = x
+        hbalhelper n x y = hbalhelper (n-1) [Branch 'x' l r| let tl = x ++ y, l <- tl, r <- tl] x
diff --git a/H60.hs b/H60.hs
new file mode 100644
index 0000000..6f3f1b0
--- /dev/null
+++ b/H60.hs
@@ -0,0 +1,18 @@
+import Tree
+import H59
+
+import Data.Maybe
+import Data.List
+
+hbalTreeNodes :: Int -> [Tree Char]
+hbalTreeNodes 0 = [Empty]
+hbalTreeNodes n = concatMap (filter ((==n).countNodes).hbalTree') [minH..maxH]
+    where 
+        -- Shenle
+        minNodesSeq = 0:1:zipWith ((+).(1+)) minNodesSeq (tail minNodesSeq)
+        
+        minH = ceiling $ logBase 2 $ fromIntegral (n+1)
+        maxH = (fromJust $ findIndex (>n) minNodesSeq) - 1
+        countNodes Empty = 0
+        countNodes (Branch _ t1 t2) = 1 + (countNodes t1) + (countNodes t2)
+
-- 
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