/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int ans = INT_MIN;
    int deal(TreeNode* root) {
        if (!root) return 0;
        int left = max(deal(root->left), 0);
        int right = max(deal(root->right), 0);
        ans = max(ans, root->val + left + right);
        return max(left, right) + root->val;
    }
    int maxPathSum(TreeNode* root) {
        // write code here
        deal(root);
        return ans;
    }
};