Problem Binary Tree Maximum Path Sum

Problem Description:

Given a binary tree, find the maximum path sum.

The path may start and end at any node in the tree.

For example:
Given the below binary tree,

       1
      /      2   3

Return 6.

Solution:

 1 public class Solution {
 2     public int max;
 3     public int maxPathSum(TreeNode root) {
 4         if (root == null) return 0;
 5         max = root.val;
 6         findMax(root);
 7         return max;
 8     }
 9     public  int findMax(TreeNode node) {
10         if (node == null) return 0;
11
12         int left = Math.max(findMax(node.left), 0);
13         int right = Math.max(findMax(node.right), 0);
14
15         max = Math.max(node.val + left + right, max);
16
17         return node.val + Math.max(left, right);
18     }
19 }

Problem Binary Tree Maximum Path Sum