16-reverse-sum-binary-tree-tmp.py

# Given a binary tree, return a simmilar binary tree such 
# that each node's value is the sum of all greater values 
# within the original tree

# Example
#
#        4
#    2       6    
#  1   3   5   7
#
#        |
#        |  converts to
#        V
#
#         22
#    27         13    
# 28    25   18     7