Update print-binary-tree.py

Author: kamyu104

Python/print-binary-tree.py

@@ -1,6 +1,55 @@
 # Time:  O(n)
 # Space: O(h)
 
+# Print a binary tree in an m*n 2D string array following these rules:
+#
+# The row number m should be equal to the height of the given binary tree.
+# The column number n should always be an odd number.
+# The root node's value (in string format) should be put in the exactly middle of the first row it can be put.
+# The column and the row where the root node belongs will separate the rest space into two parts
+# (left-bottom part and right-bottom part). You should print the left subtree in the left-bottom part and
+# print the right subtree in the right-bottom part. The left-bottom part and the right-bottom part should have the same size.
+# Even if one subtree is none while the other is not, you don't need to print anything for the none subtree
+# but still need to leave the space as large as that for the other subtree. However, if two subtrees are none,
+# then you don't need to leave space for both of them.
+# Each unused space should contain an empty string "".
+# Print the subtrees following the same rules.
+# Example 1:
+# Input:
+#      1
+#     /
+#    2
+# Output:
+# [["", "1", ""],
+#  ["2", "", ""]]
+# Example 2:
+# Input:
+#      1
+#     / \
+#    2   3
+#     \
+#      4
+# Output:
+# [["", "", "", "1", "", "", ""],
+#  ["", "2", "", "", "", "3", ""],
+#  ["", "", "4", "", "", "", ""]]
+# Example 3:
+# Input:
+#       1
+#      / \
+#     2   5
+#    / 
+#   3 
+#  / 
+# 4 
+# Output:
+#
+# [["",  "",  "", "",  "", "", "", "1", "",  "",  "",  "",  "", "", ""]
+#  ["",  "",  "", "2", "", "", "", "",  "",  "",  "",  "5", "", "", ""]
+#  ["",  "3", "", "",  "", "", "", "",  "",  "",  "",  "",  "", "", ""]
+#  ["4", "",  "", "",  "", "", "", "",  "",  "",  "",  "",  "", "", ""]]
+# Note: The height of binary tree is in the range of [1, 10].
+#   
 # Definition for a binary tree node.
 # class TreeNode(object):
 #     def __init__(self, x):
@@ -27,7 +76,7 @@ def getHeight(root):
         def preorderTraversal(root, level, left, right, result):
             if not root:
                 return
-            mid = left + (right - left) / 2
+            mid = left + (right-left)/2
             result[level][mid] = str(root.val)
             preorderTraversal(root.left, level+1, left, mid-1, result)
             preorderTraversal(root.right, level+1, mid+1, right, result)