Convert Sorted List to Binary Search Tree

/*

Convert Sorted List to Binary Search Tree

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

*/
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
TreeNode *findMidNode(ListNode *head){
        if(head==NULL) return NULL;
    ListNode *prev = NULL;
        ListNode *curr = head;
        ListNode *tail = curr->next;
        if(tail!=NULL) tail = tail->next;
        while(tail!=NULL){
prev = curr;
            curr = curr->next;
            tail = tail->next;
            if(tail!=NULL) tail = tail->next;
        }
if(curr==NULL) return NULL;
TreeNode *node = new TreeNode(curr->val);
        if(prev!=NULL) prev->next = NULL;
        if(head!=curr) node->left = findMidNode(head);
        node->right = findMidNode(curr->next);
        return node;
    }
   
    TreeNode *sortedListToBST(ListNode *head) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(head==NULL) return NULL;
        if(head->next==NULL){
           TreeNode* root = new TreeNode(head->val);
           return root;
        }
       
        return findMidNode(head);
    }
};