[leetcode] Binary Tree Maximum Path Sum

Given a binary tree, find the maximum path sum.

The path may start and end at any node in the tree.

For example:
Given the below binary tree,

       1
      / \
     2   3

Return 6.

class Solution {
public:
    int maxPathSum(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int tmp=-99999999;
        if(!root)
            return 0;
        maxPathSum2(root,tmp);
        return tmp;
    }
    int maxPathSum2(TreeNode *root , int &path){
        int lefttmp=-99999999;
        int righttmp=-99999999;
        if(!root)
            return -99999999;
        if(root->left)
            lefttmp=maxPathSum2(root->left,path);
        if(root->right)
            righttmp=maxPathSum2(root->right,path);
        path=max(max(max(max(max(lefttmp,righttmp),root->val),lefttmp+root->val),righttmp+root->val),righttmp+lefttmp+root->val);

        return max(max(max(righttmp+root->val,-99999999),lefttmp+root->val),root->val);

    }
};