最近刷leetcode，关于链表的题都很生疏，决定认认真真自己实现一遍。
#1.定义链表的基本元素：节点Node
class Node(object):
'''
data 保存节点的数据
next 保存下一个节点的对象
'''
def __init__(self, data=None, pnext=None):
self.data = data
self.pnext = pnext
def __repr__(self):
'''
用来定义 Node 的字符输出，
print为输出data
'''
return str(self.data)
#2.把node连接起来
# （1）定义一个个的节点
node1 = Node(1)
node2 = Node(2)
node3 = Node(3)
# （2）表示出节点间的关系
node1.pnext = node2
node2.pnext = node3
#3.打印链表
# (1)顺序打印
def printlist(node):
while node:
print(node)
node = node.pnext
# printlist(node1)
# (2)逆序打印
def backwardprintlist(node):
if node == None:
return
backwardprintlist(node.pnext)
print(node)
# backwardprintlist(node1)
#4. 创建一个单链表&链表的基本操作
class Slinkedlist(object):
def __init__(self):
self.headval = None
def append(self, newdata):
'''
在链表的末尾添加一个新的node
'''
newnode = Node(newdata)
if self.headval is None:
self.headval = newnode
return
# 只有遍历一遍才能找到最后一个元素
laste = self.headval
while laste.pnext:
laste = laste.pnext
laste.pnext = newnode
def forwardprint(self):
'''顺序打印单链表'''
printval = self.headval
while printval:
print(printval)
printval = printval.pnext
def backwardprint(self, node):
'''逆序打印单链表'''
if self.headval == None: return
printval = node
if printval == None: return
self.backwardprint(printval.pnext)
print(printval)
def add_left(self, newdata_in):
'''在链表的开头插入一个node'''
newdata_in = Node(newdata_in)
newdata_in.pnext = self.headval
self.headval = newdata_in
def insert(self, selected_node, newdata_in):
'''在链表的两个元素之间插一个元素'''
if not selected_node:
print('error: the node methioned does not exsist')
newnode_in = Node(newdata_in)
newnode_in.pnext = selected_node.pnext
selected_node.pnext = newnode_in
def delete(self, removekey):
'''删除指定位置的node'''
if removekey is None:
return
if self.headval is None:
print('The single list is empty!')
return
if self.headval.data == removekey:
self.headval = self.headval.pnext
return
pre_node = self.headval
cur_node = self.headval.pnext
while cur_node is not None:
if cur_node.data == removekey:
pre_node.pnext = cur_node.pnext
return
else:
pre_node = cur_node
cur_node = cur_node.pnext
# test
l = Slinkedlist()
for i in range(6):
l.append(i)
l.add_left(7)
l.insert(l.headval.pnext.pnext, 'haha')
# l.forwardprint()
# l.backwardprint(l.headval)
l.delete(5)
l.forwardprint()
