现在在地基系统学习python，记录一下自己每天学习python的日常，今天在刷题的时候看到一道题是要用链表做的，自己忘的差不多了，重新学习一下，希望也对大家有所帮助，每天学习内容太多了，没时间仔细写注解，直接放代码和结果了
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python 单链表的基本操作
例如：
- 链表创建
- 节点的增删查改
- 链表反转
代码块：
class ListNode:
def __init__(self, val):
self.val = val # 值
self.next = None
class LinkedList:
def __init__(self):
self.head = None # 头节点
self.tail = None # 尾节点
def isEmpty(self): # 判断链表是否为空
return self.head is None # 空链表返回1
def size(self): # 统计链表节点个数
if self.isEmpty():
print("链表为空")
return
cur = self.head
count = 0
while cur:
count += 1
cur = cur.next
return count
def append(self, val): # 尾插 参数：插入的单个值
node = ListNode(val)
if self.head is None:
self.head = node
self.tail = node
else:
self.tail.next = node
self.tail = node
def appendList(self, list): # 尾插 参数:插入的列表
for i in list[0:]:
node = ListNode(i)
if self.head is None:
self.head = node
self.tail = node
else:
self.tail.next = node
self.tail = node
def printAll(self): # 输出所有元素
if self.isEmpty():
print("链表为空")
return
cur = self.head
while cur:
print(cur.val, end='t')
cur = cur.next
print()
def printVal(self): # 调用next（）逐个输出 g = list.printVal() print(next(g))
if self.isEmpty():
print("链表为空")
return
cur = self.head
while cur:
yield cur.val
cur = cur.next
print("已到尾节点")
return
def insert(self, index, value): # 插入节点 头结点下标为0 参数：插入节点下标（插入后的链表节点下标） 插入值
if self.isEmpty():
print("链表为空")
return
if index > self.size():
print(f'边界值为:{self.size()}，已超过边界值')
return
cur = self.head
if index == 0: # 插入的节点为头节点时，更新头节点
node = ListNode(value)
node.next = self.head
self.head = node
return
while index - 1:
cur = cur.next
index -= 1
node = ListNode(value)
if not cur.next: # 插入节点为尾节点时，更新尾节点
self.tail = node
node.next = cur.next
cur.next = node
def update(self, index, value): # 修改某一节点值
if self.isEmpty():
print("链表为空")
return
if index >= self.size():
print(f'边界值为:{self.size()}，已超过边界值')
return
cur = self.head
while index:
cur = cur.next
index -= 1
cur.val = value
print("修改成功")
def delete(self, index): # 删除节点 头节点为0 参数：节点下标（当前链表节点下标）
if self.isEmpty():
print("链表为空")
return
if index >= self.size():
print(f'边界值为:{self.size()}，已超过边界值')
return
if self.head is self.tail: # 删除只有一个节点的链表
self.head = None
self.tail = None
return
if index == 0: # 删除头节点时，头节点重新赋值
self.head = self.head.next
return
cur = self.head
while index - 1:
cur = cur.next
index -= 1
cur.next = cur.next.next # 删除对应节点
if not cur.next: # 删除尾节点时，尾节点重新赋值
self.tail = cur
def reverse(self): # 链表反转
newHead = None
cur = self.head
while cur:
cur2 = ListNode(cur.val) # 头插
cur2.next = newHead
newHead = cur2
cur = cur.next
self.head = newHead
print("反转成功")
return
def search(self, value):#查询某个值
cur = self.head
index = 0
while cur:
if cur.val == value:
print(f"数值{value}在第{index}个节点")
return
index += 1
cur = cur.next
print("数值不存在")
list = LinkedList()
print("==插入单个数值==")
list.append(0)
list.printAll()
print("==插入链表==")
list.appendList([1, 2, 3, 4])
list.printAll()
print("==统计节点数==")
print(list.size())
print("==调用next逐个输出==")
func = list.printVal()
print(next(func))
print(next(func))
print("==插入节点==")
list.insert(5, 5)
list.printAll()
print("==删除节点==")
list.delete(5)
list.printAll()
print("==修改节点==")
list.update(4, 8)
list.printAll()
print("==反转链表==")
list.reverse()
list.printAll()
--- # 运行结果：  
