binary-tree-maximum-path-sum leetcode C++

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

Return6.

C++

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
    int maxDis;
public:
    int maxPathSum(TreeNode *root) {
        if(!root){
            maxDis=0;
            return -1e8;
        }
        int leftMax=maxPathSum(root->left);
        int l=max(0,maxDis);
        int rightMax=maxPathSum(root->right);
        int r=max(0,maxDis);
        maxDis=max(l,r)+root->val;
        return max(leftMax,max(rightMax,l+r+root->val));
    }
};