Medium Accuracy: 34.85% Submissions: 31714 Points: 4

Given a Binary Tree, you need to find the maximum value which you can get by subtracting the value of node B from the value of node A, where A and B are two nodes of the binary tree and A is an ancestor of B.

Example 1:

Input:
5
/ \
2 1
Output: 4
Explanation:The maximum difference we can
get is 4, which is bewteen 5 and 1.

Example 2:

Input:
1
/ \
2 3
\
7
Output: -1
Explanation:The maximum difference we can
get is -1, which is between 1 and 2.

Your Task:
The task is to complete the function maxDiff() which finds the maximum difference between the node and its ancestor.

Expected Time Complexity: O(N). Expected Auxiliary Space: O(H).
Note: H is the height of the tree.

Constraints:
1 <= Number of edges <= 10^{4}
0 <= Data of a node <= 10^{5}

Note: The Input/Output format and Examples given are used for the 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 the stdin/console. The task is to complete the function specified, and not to write the full code.