Maximum Path Sum between 2 Leaf Nodes
Hard Accuracy: 49.92% Submissions: 100k+ Points: 8

Given a binary tree in which each node element contains a number. Find the maximum possible path sum from one leaf node to another leaf node.

Note: Here Leaf node is a node which is connected to exactly one different node.

Example 1:

Input:
3
/    \
4       5
/  \
-10   4
Output: 16
Explanation:
Maximum Sum lies between leaf node 4 and 5.
4 + 4 + 3 + 5 = 16.


Example 2:

Input:
-15
/      \
5         6
/  \       / \
-8    1     3   9
/  \              \
2   -3              0
/ \
4  -1
/
10
Output:  27
Explanation:
The maximum possible sum from one leaf node
to another is (3 + 6 + 9 + 0 + -1 + 10 = 27)

You dont need to read input or print anything. Complete the function maxPathSum() which takes root node as input parameter and returns the maximum sum between 2 leaf nodes.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(Height of Tree)

Constraints:
2  ≤  Number of nodes  ≤  104
-103  ≤ Value of each node ≤ 103

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