题目

解题

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next


class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        # 创建一个虚拟头结点
        dummy = ListNode(0)
        dummy.next = head
        prev = dummy

        while head:
            # 检查当前节点是否是重复节点
            if head.next and head.val == head.next.val:
                # 找到所有重复的节点
                while head.next and head.val == head.next.val:
                    head = head.next
                # 跳过所有重复的节点
                prev.next = head.next
            else:
                # 如果没有重复,更新 prev
                prev = prev.next

            # 移动到下一个节点
            head = head.next

        return dummy.next


# 工具函数
def print_linked_list(head: ListNode):
    """打印链表中的所有节点值"""
    current = head
    while current:
        print(current.val, end=" -> " if current.next else "\n")
        current = current.next


def list_to_linked_list(values):
    """将列表转换为链表"""
    if not values:
        return None
    dummy = ListNode(0)
    current = dummy
    for value in values:
        current.next = ListNode(value)
        current = current.next
    return dummy.next


def linked_list_to_list(head: ListNode):
    """将链表转换为列表"""
    result = []
    current = head
    while current:
        result.append(current.val)
        current = current.next
    return result


# 测试代码
if __name__ == "__main__":
    # 测试案例
    test_cases = [
        ([1, 1, 1, 2, 3], [2, 3]),  # 删除重复元素后的链表
        ([1, 1, 2, 3, 3], [2]),  # 删除重复元素后的链表
        ([1, 2, 3, 4, 5], [1, 2, 3, 4, 5]),  # 无重复元素
        ([1, 1, 2, 2, 3, 3], []),  # 所有元素都重复
        ([1, 2, 3, 4, 4, 5, 5], [1, 2, 3])  # 删除重复元素后的链表
    ]

    for i, (values, expected) in enumerate(test_cases):
        head = list_to_linked_list(values)
        solution = Solution()
        print(f"测试用例 {i + 1}: 原链表:", end="")
        print_linked_list(head)
        new_head = solution.deleteDuplicates(head)
        result = linked_list_to_list(new_head)
        print(f"删除重复元素后的链表:", end="")
        print_linked_list(new_head)
        assert result == expected, f"测试失败:期望 {expected}, 但得到 {result}"
        print("测试通过\n")
08-03 17:10