我是Stackoverflow和Python语言的新手,并且有一个问题。我知道如何在Python中实现单个链接的列表,但是在双重链接列表中遇到麻烦,更具体地说是将其插入双链接列表的中间。谁能帮我执行代码?谢谢
我也是Python的新手,但我希望我能为您提供帮助。因此,如果我正确收到您的问题,假设您有一些(经典)链接列表实现这样:
# Simple LinkedList class
class LinkedList:
def __init__(self, data, prev=None, next=None):
self.data = data
self.prev = prev
self.next = next
# Just a string representation
def __str__(self):
if self.next:
return '%s %s' % (str(self.data), self.next.__str__())
else:
return '%s' % str(self.data)
通过同时从末端到中间迭代,您可以轻松地将元素插入中间。当迭代器相交时,您添加了元素:
# Insert to middle logic
def insertToMiddle(data, left, right):
# Iterate
while True:
# Test for intersection
if left.next is right:
node = LinkedList(data, left, right)
left.next = node
right.prev = node
return
elif left is right:
node = LinkedList(data, left.prev, right.next)
left.next = node
right.next.prev = node
return
# Next iteration
left = left.next
right = right.prev
# This doesn't actually execute for a right call
if not left or not right:
return
下面,您可以在插入之前和之后看到链接的列表创建及其表示形式:
# Sample list creation
node1 = LinkedList(1)
node2 = LinkedList(2,node1)
node3 = LinkedList(3,node2)
node4 = LinkedList(4,node3)
node1.next = node2
node2.next = node3
node3.next = node4
# Test
print node1
insertToMiddle(5, node1, node4)
print node1
insertToMiddle(6, node1, node4)
print node1
insertToMiddle(7, node1, node4)
print node1
输出:
1 2 3 4 #initial
1 2 5 3 4 #inserted 5
1 2 5 6 3 4 #inserted 6, notice it's right to middle
1 2 5 7 6 3 4 #inserted 7
备注:如果您的列表具有奇数元素(例如2 3 4),则插入到中间是不确定的,因此上述功能将立即添加到中间的右边(2 3 Elem 4)