From 28460715b62e83a89f32db41a9bcafae19f31b5e Mon Sep 17 00:00:00 2001
From: Flow-sandyu <72751523+Flow-sandyu@users.noreply.github.com>
Date: Tue, 27 Sep 2022 20:39:27 +0800
Subject: [PATCH 1/2] =?UTF-8?q?Update=200019.=E5=88=A0=E9=99=A4=E9=93=BE?=
 =?UTF-8?q?=E8=A1=A8=E7=9A=84=E5=80=92=E6=95=B0=E7=AC=ACN=E4=B8=AA?=
 =?UTF-8?q?=E8=8A=82=E7=82=B9.md?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

修改了0019.删除链表的倒数第N个节点  java 版本
---
 ...0019.删除链表的倒数第N个节点.md | 43 ++++++++++---------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/problems/0019.删除链表的倒数第N个节点.md b/problems/0019.删除链表的倒数第N个节点.md
index 00caeea0..c7f79b8d 100644
--- a/problems/0019.删除链表的倒数第N个节点.md
+++ b/problems/0019.删除链表的倒数第N个节点.md
@@ -87,30 +87,31 @@ public:
 java:
 
 ```java
-class Solution {
-    public ListNode removeNthFromEnd(ListNode head, int n) {
-        ListNode dummy = new ListNode(-1);
-        dummy.next = head;
+public ListNode removeNthFromEnd(ListNode head, int n){
+    ListNode dummyNode = new ListNode(0);
+    dummyNode.next = head;
 
-        ListNode slow = dummy;
-        ListNode fast = dummy;
-        while (n-- > 0) {
-            fast = fast.next;
-        }
-        // 记住 待删除节点slow 的上一节点
-        ListNode prev = null;
-        while (fast != null) {
-            prev = slow;
-            slow = slow.next;
-            fast = fast.next;
-        }
-        // 上一节点的next指针绕过 待删除节点slow 直接指向slow的下一节点
-        prev.next = slow.next;
-        // 释放 待删除节点slow 的next指针, 这句删掉也能AC
-        slow.next = null;
+    //排除示例 2 的情况：head = [1], n = 1
+    if (head == null)
+        return null;
 
-        return dummy.next;
+    ListNode fastIndex = dummyNode;
+    ListNode slowIndex = dummyNode;
+
+    //只要快慢指针相差 n 个结点即可
+    for (int i = 0; i < n  ; i++){
+        fastIndex = fastIndex.next;
     }
+
+    while (fastIndex.next != null){
+        fastIndex = fastIndex.next;
+        slowIndex = slowIndex.next;
+    }
+
+    //此时 slowIndex 的位置就是待删除元素的前一个位置。
+    //具体情况可自己画一个链表长度为 3 的图来模拟代码来理解
+    slowIndex.next = slowIndex.next.next;
+    return dummyNode.next;
 }
 ```
 

From 87c505371df01e7d62e422b796de66d92754fced Mon Sep 17 00:00:00 2001
From: Flow-sandyu <72751523+Flow-sandyu@users.noreply.github.com>
Date: Tue, 27 Sep 2022 21:01:31 +0800
Subject: [PATCH 2/2] =?UTF-8?q?Update=200019.=E5=88=A0=E9=99=A4=E9=93=BE?=
 =?UTF-8?q?=E8=A1=A8=E7=9A=84=E5=80=92=E6=95=B0=E7=AC=ACN=E4=B8=AA?=
 =?UTF-8?q?=E8=8A=82=E7=82=B9.md?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0019.删除链表的倒数第N个节点.md | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/problems/0019.删除链表的倒数第N个节点.md b/problems/0019.删除链表的倒数第N个节点.md
index c7f79b8d..a84c0b29 100644
--- a/problems/0019.删除链表的倒数第N个节点.md
+++ b/problems/0019.删除链表的倒数第N个节点.md
@@ -91,10 +91,6 @@ public ListNode removeNthFromEnd(ListNode head, int n){
     ListNode dummyNode = new ListNode(0);
     dummyNode.next = head;
 
-    //排除示例 2 的情况：head = [1], n = 1
-    if (head == null)
-        return null;
-
     ListNode fastIndex = dummyNode;
     ListNode slowIndex = dummyNode;