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Transform to Sum Tree
Submissions: 19398   Accuracy:


  Difficulty: Easy   Marks: 2

Given a Binary Tree of size N , where each node has positive and negative values. Convert this to a tree where each node contains the sum of the left and right sub trees in the original tree. The values of leaf nodes are changed to 0.

For example, the following tree

          /      \
        -2        6
       /   \     /  \
     8     -4   7    5

should be changed to

          /              \
     4(8-4)      12(7+5)
       /   \           /  \
     0      0       0    0


First line of input contains the number of test cases T. For each test case, there will be only a single line of input which is a string representing the tree as described below: 

  1. The values in the string are in the order of level order traversal of the tree where, numbers denotes node values, and a character “N” denotes NULL child.

  2. For example:

    For the above tree, the string will be: 1 2 3 N N 4 6 N 5 N N 7 N

Inorder traversal of modified tree , printed by driver code.

Your Task:
You don't need to take input. Just complete the function toSumTree() which accepts root node of the tree as a parameter and modify tree into SumTree.
Expected Time Complexity: O(N).
Expected Auxiliary Space: O(Height of the Tree).

1 <=T<= 100
1 <= N <= 104


3 1 2
10 20 30 40 60

0 3 0

0 100 0 150 0

Note:The Input/Ouput format and Example given are used for system's internal purpose, and should be used by a user for Expected Output only. As it is a function problem, hence a user should not read any input from stdin/console. The task is to complete the function specified, and not to write the full code.

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: Saksham Raj Seth
Author: kartik

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