Update 0203.移除链表元素.md

problems/0203.移除链表元素.md

@@ -307,21 +307,27 @@ public ListNode removeElements(ListNode head, int val) {
 Python：
 
 ```python
+（版本一）虚拟头节点法
 # Definition for singly-linked list.
 # class ListNode:
 #     def __init__(self, val=0, next=None):
 #         self.val = val
 #         self.next = next
 class Solution:
-    def removeElements(self, head: ListNode, val: int) -> ListNode:
-        dummy_head = ListNode(next=head) #添加一个虚拟节点
-        cur = dummy_head
-        while cur.next:
-            if cur.next.val == val:
-                cur.next = cur.next.next #删除cur.next节点
+    def removeElements(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:
+        # 创建虚拟头部节点以简化删除过程
+        dummy_head = ListNode(next = head)
+        
+        # 遍历列表并删除值为val的节点
+        current = dummy_head
+        while current.next:
+            if current.next.val == val:
+                current.next = current.next.next
             else:
-                cur = cur.next
+                current = current.next
+        
         return dummy_head.next
+
 ```
 
 Go：