/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    int getMax(TreeNode *root){            if(root == NULL) return 0;        int left = getMax(root->left);        int right = getMax(root->right);                //左子树经过当前节点到右子树的路径        int cur = root->val ;        if(left > 0 ) cur += left;        if(right > 0) cur += right;        res = res < cur ? cur : res;                int up = left > right ? left : right;        up = up > 0 ? up  : 0;           return up + root->val;    }    int maxPathSum(TreeNode *root) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(NULL == root) return 0;        res = root->val;        getMax(root);        return res;    }private:    int res;};