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

    @classmethod
    def deletenodeo1(cls, pheadNode, pToBedeleted):
        # 1.如果链表只有一个节点
        # 2.如果删除的节点是链表的尾节点
        # 3.多节点：把当前给定节点的next的data赋值给，再把i.next=j.next del j即可
        if not pheadNode or not pToBedeleted:
            return

        if pToBedeleted.next:  # 说明当前节点和当前节点的下一个元素 和下下一个节点都有之  第3种情况
            next = pToBedeleted.next
            next__next = pToBedeleted.next.next
            pToBedeleted.data = next.data
            pToBedeleted.next = next__next
            del next
        elif pheadNode == pToBedeleted:  # 删除头节点
            del pheadNode
        else:  # 删除尾节点
            # O(n)遍历删除最后一个节点
            while pheadNode.next != pToBedeleted:
                pheadNode = pheadNode.next
            pheadNode.next = None
            del pToBedeleted


a = ListNode('a')
b = ListNode('b')
c = ListNode('c')
d = ListNode('d')

root = a


# a.next = b
# b.next = c
# c.next = d


def travese(root):
    while root:
        print(root.data)
        root = root.next


# 1.删除尾节点
ListNode.deletenodeo1(root, a)
travese(root)