class Node():
def __init__(self, data = None, next = None, pre = None):
self.data = data # 常量
self.next = next # Node
self.pre = pre
def setData(self, data):
self.data = data
def setNext(self, next):
self.next = next
def getData(self):
return self.data
# [1,2,3]
# node1 = Node(data=3)
# node2 = Node(data=2, next = node1)
# node3 = Node(data=1, next = node2)
class LinkedList():
def __init__(self, node = None):
self.head = node
self.tail = node
#判断是否为空
def isempty(self):
return self.head == None
# 从头部加入一个元素/结点
def add(self, item):
# 实例化
tmp = Node(item)
if self.isempty():
self.head = tmp
else:
tmp.setNext(self.head)
self.head = tmp
#从尾部添加一个元素
def append(self, item):
#实例化
tmp = Node(item)
#尾部指针
end = self.tail
end.setNext(tmp)
self.tail = tmp
#遍历
def travel(self):
if not self.head:
return self.head
else:
cur = self.head
while cur:
print(cur.data, end=" ")
cur = cur.next
print("\n")
#插入
def insert(self, index, data):
if self.isempty():
print("链表为空")
return
else:
# 实例化
tmp = Node(data)
# 索引
cur = -1
pre_node = Node(next=self.head)
# cur = index
while cur<index:
# 结点和索引同步更新
pre_node = pre_node.next
cur += 1
if not pre_node:
print("插入的位置:{}越界".format(index))
return
# 插入
tmp.setNext(pre_node.next)
pre_node.setNext(tmp)
#删除
def remove(self, index):
if self.isempty():
print("链表为空")
return
elif index == 0:
self.head = self.head.next
else:
# 索引
cur = 0
# 前置结点
pre = self.head
# 想退出的是cur = index - 1
while cur < index-1:
# 同步更新
cur += 1
pre = pre.next
# 判断是否到达尾部
if not pre.next:
print("越界")
return
# 删除
pre.setNext(pre.next.next) # pre tmp = pre.next pre.next.next None!=Node tail.next = None
if __name__ == "__main__":
node1 = Node(1)
node2 = Node(2)
node3 = Node(3)
list = LinkedList(node1)
list.add(2)
list.add(3)
list.append(4)
list.travel()
list.insert(3,5)
list.travel()
list.insert(10,9)
list.remove(4)
list.travel()
Python实现链表的增删遍历
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