81: Convert binary search tree to greater tree

Given a binary search tree, convert to a greater tree such that every value of the given tree is changed to the original value plus sum of all values greater than the original value in the tree

 

Example 1

Input:        5  
             / \
            3   6

Output:       11
             /  \
            14   6

Example 2

Input:     1  
            \  
             3 

Output:    4
            \
             3