From dedb4aaced15ddfdf1817c1bd047fb03a248903e Mon Sep 17 00:00:00 2001
From: ZhongGuanbin <93035140+ZhongGuanbin@users.noreply.github.com>
Date: Sat, 28 Sep 2024 09:13:18 +0800
Subject: [PATCH] Update linked_list.md (#1521)
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双向链表的Dart代码可能存在语法错误，因为前驱节点和后继节点可能为空，所以需要添加问号，否则无法通过空安全检查
---
 docs/chapter_array_and_linkedlist/linked_list.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/chapter_array_and_linkedlist/linked_list.md b/docs/chapter_array_and_linkedlist/linked_list.md
index 0c97329f5..07750e6a9 100755
--- a/docs/chapter_array_and_linkedlist/linked_list.md
+++ b/docs/chapter_array_and_linkedlist/linked_list.md
@@ -635,8 +635,8 @@
     /* 双向链表节点类 */
     class ListNode {
         int val;        // 节点值
-        ListNode next;  // 指向后继节点的引用
-        ListNode prev;  // 指向前驱节点的引用
+        ListNode? next;  // 指向后继节点的引用
+        ListNode? prev;  // 指向前驱节点的引用
         ListNode(this.val, [this.next, this.prev]);  // 构造函数
     }
     ```