1 class Solution {
2 int maxValue;
3 public int maxPathSum(TreeNode root) {
4 maxValue = Integer.MIN_VALUE;
5 maxPathDown(root);
6 return maxValue;
7 }
8
9 private int maxPathDown(TreeNode node) {
10 if (node == null) return 0;
11 int left = Math.max(0, maxPathDown(node.left));
12 int right = Math.max(0, maxPathDown(node.right));
13 maxValue = Math.max(maxValue, left + right + node.val);
14 return Math.max(left, right) + node.val;
15 }
16 }
参考：https://leetcode.com/problems/binary-tree-maximum-path-sum/discuss/39775/Accepted-short-solution-in-Java
