# # 单向链表
# class Node(object):
# def __init__(self, elem):
# self.elem = elem
# self.next = None
#
# class SingleLink(object):
# def __init__(self, node=None):
# self.__node = node
#
# def is_empty(self):
# # 链表是否为空
# return self.__node == None
#
# def length(self):
# # 链表长度
# # cur游标，用来移动遍历节点
# cur = self.__node
# count = 0
# while cur != None:
# count += 1
# cur = cur.next
# return count
#
# def travel(self):
# # 遍历整个链表
# cur = self.__node
# while cur != None:
# # cur从一开始就是赋予的头结点，而节点本身是有数据区和指针区的
# print(cur.elem)
# cur = cur.next
#
# def add(self, item):
# # 链表头部添加元素
# node = Node(item)
# node.next = self.__node
# self.__node = node
#
# def append(self, item):
# # 链表尾部添加元素
# node = Node(item)
# cur = self.__node
# if self.is_empty():
# self.__node = node
# else:
# while cur.next != None:
# cur = cur.next
# cur.next = node
#
# def insert(self, pos, item):
# # 指定位置添加元素
# if pos <= 0:
# self.add(item)
# elif pos > (self.length() - 1):
# self.append(item)
# else:
# pre = self.__node
# count = 0
# while count < (pos - 1):
# count += 1
# pre = pre.next
# # 当循环退出时，pre指向pos-1
# node = Node(item)
# node.next = pre.next
# pre.next = node
#
# def remove(self, item):
# # 删除节点
# pass
#
# def search(self, item):
# # 查找节点是否存在
# cur = self.__node
# while cur != None:
# if item == cur.elem:
# return True
# else:
# cur = cur.next
# return False
#
# # node = Node(100)
# # single_obj = SingleLink()
# # single_obj.travel()
#
# if __name__ == '__main__':
# ll = SingleLink()
# print(ll.is_empty())
# print(ll.length())
#
# ll.append(1)
# print(ll.is_empty())
# print(ll.length())
#
# ll.append(2)
# ll.add(8)
# ll.append(3)
# ll.travel()
#
# ll.insert(-1, 9)
# ll.insert(3, 100)
class Node(object):
"""节点"""
def __init__(self, elem):
self.elem = elem
self.next = None
class SingleLinkList(object):
"""单链表"""
def __init__(self, node=None):
self.__head = node
def is_empty(self):
"""链表是否为空"""
return self.__head == None
def length(self):
"""链表长度"""
# cur游标，用来移动遍历节点
cur = self.__head
# count记录数量
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历整个链表"""
cur = self.__head
while cur != None:
print(cur.elem, end=" ")
cur = cur.next
print("")
def add(self, item):
"""链表头部添加元素，头插法"""
node = Node(item)
node.next = self.__head
self.__head = node
def append(self, item):
"""链表尾部添加元素, 尾插法"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
def insert(self, pos, item):
"""指定位置添加元素
:param pos 从0开始
"""
if pos <= 0:
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
pre = self.__head
count = 0
while count < (pos - 1):
count += 1
pre = pre.next
# 当循环退出后，pre指向pos-1位置
node = Node(item)
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除节点"""
cur = self.__head
pre = None
while cur != None:
if cur.elem == item:
# 先判断此结点是否是头节点
# 头节点
if cur == self.__head:
self.__head = cur.next
else:
pre.next = cur.next
break
# print('死循环？？？？？？？？？？？？？？') 不加break这里形成了一个死循环，不知道为什么？
# 因为cur = cur.next这一步没执行，始终还是在判断游标与原来元素一致的这种条件
else:
pre = cur
cur = cur.next
def search(self, item):
"""查找节点是否存在"""
cur = self.__head
while cur != None:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == "__main__":
ll = SingleLinkList()
print(ll.is_empty())
print(ll.length())
ll.append(1)
print(ll.is_empty())
print(ll.length())
ll.append(2)
ll.add(8)
ll.append(3)
ll.append(4)
ll.append(5)
ll.append(6)
# 8 1 2 3 4 5 6
ll.insert(-1, 9) # 9 8 1 23456
ll.travel()
ll.insert(3, 100) # 9 8 1 100 2 3456
ll.travel()
ll.insert(10, 200) # 9 8 1 100 23456 200
ll.travel()
ll.remove(100)
ll.travel()
ll.remove(9)
ll.travel()
ll.remove(200)
ll.travel()
