# -*- coding: utf-8 -*-
# @Time : 2018/9/28 22:09
# @Author : cxa
# @File : node.py
# @Software: PyCharm
# 单向列表
# 数据元素区，下一个结点的链接区
# 尾节点指向的结点为空。
"""
表元素域 下一结点链接域
"""
class Node:
# 结点类
def __init__(self, elem):
self.elem = elem
self.next = None
class SingLinkList(object):
# 链表类
def __init__(self, node=None):
self.__head = node
def is_empty(self):
"""列表是否为空"""
return self.__head == None
def length(self):
"""结点的数目，到尾节点截止。需要一个游标、来记录当前的位置"""
cur = self.__head
"""count记录数量,如果空链表也可以正确处理"""
count = 0
"""开始游标移动"""
while cur:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历列表"""
cur = self.__head
while cur:
print("当前的结点", cur.elem, end='')
cur = cur.next
def add(self, item):
"""从头部添加,头插法"""
node = Node(item)
node.next = self.__head
self.__head = node
def append(self, item):
"""从尾部添加,尾插法"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next:
cur = cur.next
cur.next = node
def insert(self, pos, item):
node = Node(item)
'''
从指定位置添加
:param pos: 从0开始
:param item:
:return:
'''
if pos <= 0:
self.add(item)
elif pos > self.length(item) - 1:
self.append(item)
else:
pre = self.__head # pre指前一个对象
count = 0
while count < pos - 1:
count += 1
pre = pre.next
# pre指向poss-1
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除结点"""
# pre.next=pre.next.next
cur = self.__head
pre = None
while cur:
if cur.elem == item:
# 判断此节点是否是头节点
# 头节点
if cur == self.__head:
self.__head = cur.next
else:
pre.next = cur.next
break
else:
pre = cur
cur = cur.next
def search(self, item):
"""查找结点是否存在"""
cur = self.__head
while cur:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == '__main__':
# 测试下正确性
ll = SingLinkList()
print(ll.is_empty())
print(ll.length())
ll.append(1)
print(ll.is_empty())
print(ll.length())
ll.append(2)
ll.append(3)
ll.add(8)
ll.append(4)
ll.travel()
