二叉树的最大节点

class Solution {public:    /**     * @param root the root of binary tree     * @return the max node     */     TreeNode *final;    void look(TreeNode* root)    {       if(root==NULL)       return;         if(final->val<root->val)        {         final=root;        }       look(root->left);       look(root->right);    }    TreeNode* maxNode(TreeNode* root) {        final->val=-10000;        if(root==NULL)        return NULL;        look(root);        return final;                // Write your code here    }};

水。