添加链表问题

Author: xbox1994

MD/算法-链表-双指针-删除倒数第n个.md

@@ -0,0 +1,23 @@
+https://leetcode.com/problems/remove-nth-node-from-end-of-list/
+
+给一个链表，删除倒数第n个节点
+
+```java
+class Solution {
+    public ListNode removeNthFromEnd(ListNode head, int n) {
+        ListNode dummy = new ListNode(0);
+        dummy.next = head;
+        
+        ListNode q = dummy, p = dummy;
+        while(n-->-1){
+            p = p.next;
+        }
+        while(p!=null){
+            q = q.next;
+            p = p.next;
+        }
+        q.next = q.next.next; // 优化：释放被删除节点
+        return dummy.next;
+    }
+}
+```

README.md

@@ -49,6 +49,7 @@ PS：除开知识点，一定要准备好以下套路：
 * [数组-滑动窗口-最小连续子数组](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-数组-滑动窗口-最小连续子数组.md)
 * [数组-归并排序-合并有序数组](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-数组-归并排序-合并有序数组.md)
 * [链表-链表反转-链表相加](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-链表-反转链表-链表相加.md)
+* [算法-链表-双指针-删除倒数第n个](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-链表-双指针-删除倒数第n个.md)
 * [二叉树-二叉树反转](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-二叉树-二叉树反转.md)
 * [动态规划-连续子数组最大和](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-动态规划-连续子数组最大和.md)
 * [数据结构-LRU淘汰算法](https://github.com/xbox1994/2018-Java-Interview/blob/master/MD/算法-数据结构-LRU淘汰算法.md)