class Node(object):
"""结点"""
def __init__(self, data):
self.data = data
self.next = None
class SingleLinkList(object):
"""单链表"""
def __init__(self, node=None):
# 头结点设置为私有变量
self.__head = node
def is_empty(self):
"""链表是否为空"""
return self.__head is None
def length(self):
"""链表长度"""
cur = self.__head
count = 0
while cur is not None:
cur = cur.next
count += 1
return count
def travel(self):
"""遍历整个链表"""
cur = self.__head
while cur is not None:
print(cur.data, end="")
cur = cur.next
print()
def add(self, item):
"""头插法, 在链表头部添加结点"""
node = Node(item)
node.next = self.__head
self.__head = node
def append(self, item):
"""尾插法, 在链表尾部添加结点"""
node = Node(item)
# 空链表时, 直接指向要添加的结点
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next is not None:
cur = cur.next
cur.next = node
def insert(self, pos, item):
"""指定位置添加结点"""
# 指定位置pos在第一个元素之前,执行头插法
if pos <= 0:
self.add(item)
# 指定位置超过链表尾部, 执行尾插法
elif pos > self.length() - 1:
self.append(item)
else:
# 指定位置的前一个结点
pre = self.__head
node = Node(item)
count = 0
while count < (pos - 1):
pre = pre.next
count += 1
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除结点"""
cur = self.__head
pre = None
while cur is not None:
# 找到了要删除的结点
if cur.data == item:
# 要删除的结点是头结点
if cur == self.__head:
# 将头节点指向头结点的后一个结点
self.__head = cur.next
# 要删除的结点不是头结点
else:
pre.next = cur.next
return
else:
pre = cur
cur = cur.next
def search(self, item):
"""查找结点是否存在"""
cur = self.__head
while cur is not None:
if cur.data == item:
return True
cur = cur.next
return False
if __name__ == '__main__':
sll = SingleLinkList()
print(sll.is_empty())
print(sll.length())
sll.append(1)
sll.append(2)
sll.append(3)
sll.append(4)
sll.append(5)
sll.travel() # 12345
print(sll.length()) # 5
sll.add(99) # 99 12345
sll.travel()
print(sll.length()) # 6
print(sll.search(6)) # False
print(sll.search(4)) # True
sll.remove(3)
sll.travel() # 99 1245
