#python实现数据结构单链表
# -*- coding: utf-8 -*-
class Node(object):
"""节点"""
def __init__(self, elem):
self.elem = elem
self.next = None # 节点一开始初始化的时候并不知道下一个元素的地址，所以先设置为空
class SingLinkList(object):
"""单链表"""
def __init__(self, node=None):
self.__head = node
def is_empty(self):
""""判断是否为空"""
return self.__head == None
def length(self):
"""返回长度"""
# cur游标用来移动遍历节点
cur = self.__head
# count 用来记录数量
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历链表"""
# cur游标用来移动遍历节点
cur = self.__head
# count 用来记录数量
count = 0
while cur != None:
print(cur.elem, end=' ')
cur = cur.next
print('\n')
def add(self, item):
""""链表头部添加"""
node = Node(item)
node.next = self.__head # 将新节点的next域指向首节点的头部
self.__head = node
def append(self, item):
"""链表尾部添加"""
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: pos从0 开始
:param item:
:return:
"""
if pos <= 0:
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
pre = self.__head
node = Node(item)
count = 0
while count < (pos - 1):
count += 1
pre = pre.next
# 当循环退出后pre指向pos-1
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除节点"""
pre = None
cur = self.__head
while cur != None:
if cur.elem == item:
# 判断次节点是不是头节点
# 头结点：
if cur == self.__head:
self.__head = cur.next
else:
pre.next = cur.next
break
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__':
l = SingLinkList()
print(l.is_empty())
l.add(0)
l.append(1)
l.add(8)
print(l.length())
l.append(2)
l.append(2)
l.append(4)
l.travel()
l.insert(-1, 7)
l.insert(2, 1)
l.travel()
l.remove(8)
l.travel()
# 后继节点：指的是下一个节点