remove-nth-node-from-end-of-list.cpp

class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        if (head->next == nullptr)
        {
            return nullptr;
        }

        ListNode *slow = head;
        ListNode *fast = head;

        while (n--)
        {
            fast = fast->next;
        }

        if (fast == nullptr) 
        {
            return head->next;
        }

        while (fast->next)
        {
            slow = slow->next;
            fast = fast->next;
        }

        slow->next = slow->next->next;

        return head;
    }
};