“专业人士笔记”系列目录：
创帆云：Python成为专业人士笔记--强烈建议收藏！每日持续更新！概述
链表是节点的集合，每个节点由一个索引和一个值组成，索引将所有节点串成了一个序列。自定义链表可用于实现更为复杂的数据结构，如列表、堆栈、队列和关联数组等。
自定义链表建立
本例使用与内置list对象相同的许多方法实现了一个链表
#元素节点处理类
class Node:
def __init__(self, val):
self.data = val
self.next = None
def getData(self):
return self.data
def getNext(self):
return self.next
def setData(self, val):
self.data = val
def setNext(self, val):
self.next = val
#链表类
class LinkedList:
def __init__(self):
self.head = None
def isEmpty(self):
""" 检查链表是否为空 """
return self.head is None
def add(self, item):
""" 将对象添加到链表中 """
new_node = Node(item)
new_node.setNext(self.head)
self.head = new_node
def size(self):
"""返回链表的长度"""
count = 0
current = self.head
while current is not None:
count += 1
current = current.getNext()
return count
def search(self, item):
""" 在链表中搜索项目。如果找到，返回True。如果没有找到，返回False """
current = self.head
found = False
while current is not None and not found:
if current.getData() is item:
found = True
else:
current = current.getNext()
return found
def remove(self, item):
""" 从链表中删除项目。如果在链表中没有找到项目，则引发ValueError """
current = self.head
previous = None
found = False
while current is not None and not found:
if current.getData() is item:
found = True
else:
previous = current
current = current.getNext()
if found:
if previous is None:
self.head = current.getNext()
else:
previous.setNext(current.getNext())
else:
print('未找到值')
raise ValueError
def insert(self, position, item):
"""
在指定的位置插入项目。如果指定的位置超出界限，则引发IndexError
"""
if position > self.size() - 1:
print("Index out of bounds.")
raise IndexError
current = self.head
previous = None
pos = 0
if position is 0:
self.add(item)
else:
new_node = Node(item)
while pos < position:
pos += 1
previous = current
current = current.getNext()
previous.setNext(new_node)
new_node.setNext(current)
def index(self, item):
"""
返回找到项目的索引。如果没有找到项目，则返回None。
"""
current = self.head
pos = 0
found = False
while current is not None and not found:
if current.getData() is item:
found = True
else:
current = current.getNext()
pos += 1
if found:
pass
else:
pos = None
return pos
def pop(self, position=None):
"""
如果没有提供参数，则返回并删除头部的项。如果提供了位置，则返回并删除该位 置的项。如果索引越界，则引发IndexError
"""
if position > self.size():
print('Index out of bounds')
raise IndexError
current = self.head
if position is None:
ret = current.getData()
self.head = current.getNext()
else:
pos = 0
previous = None
while pos < position:
previous = current
current = current.getNext()
pos += 1
ret = current.getData()
previous.setNext(current.getNext())
print(ret)
return ret
def append(self, item):
""" 将项追加到链表的末尾 """
current = self.head
previous = None
pos = 0
length = self.size()
while pos < length:
previous = current
current = current.getNext()
pos += 1
new_node = Node(item)
if previous is None:
new_node.setNext(current)
self.head = new_node
else:
previous.setNext(new_node)
def printList(self):
"""打印链表"""
current = self.head
while current is not None:
print(current.getData())
current = current.getNext()
#函数调用
#使用函数过程非常类似于内置list列表
ll = LinkedList()
ll.add('l') #注意函数，头部增加
ll.add('H')
ll.insert(1,'e') #指定位置添加
ll.append('l') #尾部增加
ll.append('o')
ll.printList()
#输出结果：
H
e
l
l
o
请仔细研究并在python3云环境中测试上面的代码， 如果参照以上代码已经完整实现了链表建立和操作方法，那么完全可以基于此建立自定义堆栈、队列等更复杂的数据结构
今天的分享就到这里，禁止转载，违者必究