本日耗時：30mins

19. Remove Nth Node From End of List

class Solution {
public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        ListNode* res = new ListNode(0, head);
        ListNode* dummy = res;

        for (int i = 0; i < n; i++) {
            head = head->next;
        }

        while (head != nullptr) {
            head = head->next;
            dummy = dummy->next;
        }

        dummy->next = dummy->next->next;

        return res->next;        
    }
};