19. Remove Nth Node From End of List

快慢指针定位。。

然后不用dummy node比较麻烦。。用了就很省事了。

public class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        ListNode fast = dummy;
        while (n > 0) {
            fast = fast.next;
            n--;
        }
        ListNode slow = dummy;
        while (fast.next != null) {
            fast = fast.next;
            slow = slow.next;
        }
        
        slow.next = slow.next.next;
        return dummy.next;
    }
}