LeetCode – Refresh – Binary Tree Maximum Path Sum

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     int getSum(TreeNode *root, int &gMax) {
13         if (!root) return 0;
14         int lValue = getSum(root->left, gMax), rValue = getSum(root->right, gMax), total = root->val;
15         total += lValue > 0 ? lValue : 0;
16         total += rValue > 0 ? rValue : 0;
17         gMax = max(total, gMax);
18         return max(max(root->val, root->val + lValue), root->val + rValue);
19     }
20     int maxPathSum(TreeNode *root) {
21         int gMax = INT_MIN, lMax = INT_MIN;
22         lMax = getSum(root, gMax);
23         return max(lMax, gMax);
24     }
25 };