Given a Binary Tree of size N, your task is to complete the function sumBt(), that should return the sum of all the nodes of the given binary tree.
The function takes a single arguments as input, the reference pointer to the root of the binary tree.
There are T test cases and for each test case the function will be called separately.
The function should return the sum of all the nodes of the binary tree.
1 2 L 1 3 R
10 20 L 10 30 R 20 40 L 20 60 R 30 90 L
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.