#include
     
      #include
      
       #include
       
         struct TreeNode {     int val;     TreeNode *left;     TreeNode *right;     TreeNode(int x) : val(x), left(NULL), right(NULL) {} };class Solution {public:    int maxPathSum(TreeNode *root) {        maxx(root);        return maxn;    }    int maxx(TreeNode *root)    {        if (root == NULL)return 0;        int num1 = max(0, maxx(root->left));        //注意将为负数的子树拆掉        int num2 = max(0, maxx(root->right));        maxn = max(maxn, num1 + num2 + root->val);        return max(num1, num2) + root->val;            //注意虽然为负数，但是也要返回，因为把它当成一颗数来看    }    int max(int a, int b){        return a > b ? a : b;    }    int maxn=-0x3f3f3f3f;};