python-leetcode-删除排序链表中的重复元素 II

82. 删除排序链表中的重复元素 II - 力扣（LeetCode）

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
        # 创建一个哑节点，简化对头节点的处理
        dummy = ListNode(0)
        dummy.next = head
        prev = dummy  # 指向当前已处理的最后一个节点

        while head:
            # 检查当前节点是否是重复节点
            if head.next and head.val == head.next.val:
                # 跳过所有重复的节点
                while head.next and head.val == head.next.val:
                    head = head.next
                # 让 prev 跳过这些重复节点
                prev.next = head.next
            else:
                # 如果当前节点不重复，移动 prev 指针
                prev = prev.next
            # 移动 head 指针
            head = head.next

        return dummy.next