LikedList Questions: Delete nth node from end in Two Pass

//Definition for singly-linked list.struct ListNode{    int val;    ListNode *next;    ListNode() : val(0), next(nullptr) {}    ListNode(int x) : val(x), next(nullptr) {}    ListNode(int x, ListNode *next) : val(x), next(next) {}};

ListNode *removeNthFromEnd(ListNode *head, int n)    {        //- if LL is empty        if (!head)            return head;        //note: first pass : O(n)        //- getting length of LL         int cnt = 0;        ListNode *temp = head;        while (temp)        {            cnt++;            temp = temp->next;        }        //* Standard Procedure to delete (k+1)th node from beginning        //note: Required Node: (cnt - n +1)th node        //note: we have to go "cnt-n" times deep to stand at required node        int k = cnt - n;        ListNode *cur = head;        ListNode *prev = nullptr; //it will point one node preceding to cur        //note: second pass :O(n)        while (k > 0)        {            prev = cur;            cur = cur->next;            k--;        }        //- first node of the LL is to be deleted        if (!prev)        {            temp = cur;            cur = cur->next;            delete temp;            head = cur; //! cur is the new head        }        else        {            prev->next = cur->next;            delete cur;        }        return head;    }