Table of contents
1. One-way circular linked list
One-way circular linked list graph
Second, the operation of one-way circular linked list
1. Determine whether the linked list is empty
2, the length of the linked list
3. Traverse the entire linked list
4. Add elements at the head of the linked list
5. Add elements at the end of the linked list
6. Insert an element at the specified position
7. Modify the element at the specified position
9. Find whether the element exists
related articles
Python one-way linked list operation
Operation of Python one-way circular linked list
Operation of Python doubly linked list
Operation of Python two-way circular linked list
1. One-way circular linked list
One-way circular linked list graph
There are two parts in the node node: elem (element) and next (pointer to the next node), the head pointer points to the head node, and the tail node next points to the head node
Second, the operation of one-way circular linked list
1. Determine whether the linked list is empty
def is_empty(self):
# 链表是否为空
if self.__head is None:
return True
else:
return False
2, the length of the linked list
def length(self):
# 链表长度
if self.is_empty():
return 0
count = 0
cur = self.__head
while cur.next != self.__head:
count += 1
cur = cur.next
return count
3. Traverse the entire linked list
def travel(self):
# 遍历整个链表
if self.is_empty():
return
cur = self.__head
while cur.next != self.__head:
print(cur.elem, end=' ')
cur = cur.next
print(cur.elem)
4. Add elements at the head of the linked list
def add(self, item):
# 链表头部添加元素
node = Node(item)
if self.is_empty():
self.__head = node
node.next = node
else:
tail = self.__head
# 循环找到尾结点
while tail.next != self.__head:
tail = tail.next
# 新来的节点的next指向第一个节点
node.next = self.__head
# 再改变第一个节点的指针指向新节点
self.__head = node
# 最后将尾指向指向添加node节点
tail.next = node
5. Add elements at the end of the linked list
def append(self, item):
# 链表尾部添加元素
# 创建新结点
node = Node(item)
# 是空链表就把头节点指向这个节点
if self.is_empty():
self.__head = node
node.next = node
else:
tail = self.__head
# 找到尾节点
while tail.next != self.__head:
tail = tail.next
tail.next = node
node.next = self.__head
6. Insert an element at the specified position
Traversal let the pointer point to the position to be inserted, and modify the pointing of the pointer before and after
def insert(self, pos, item):
# 位置pos在第一个元素之前，则在头部插入
if pos <= 0:
self.add(item)
# 位置pos大于总长度，则在尾部插入
elif pos > self.length():
self.append(item)
else:
# 指定位置添加元素
node = Node(item)
count = 0
pre = self.__head
# 循环定位指针位置
while count < (pos-1):
count += 1
pre = pre.next
node.next = pre.next
pre.next = node7. Modify the element at the specified position
def modify(self, pos, item):
"""修改指定位置的元素"""
# 当指定的位置pos小于等于0时，则修改头部元素
if pos <= 0:
self.__head.elem = item
# 当pos大于等于链表总长度时，则修改尾部元素
elif pos >= self.length():
tail = self.__head
# 循环让指针指向尾部元素
while tail.next != self.__head:
tail = tail.next
tail.elem = item # 修改尾部元素
else:
count = 0
tail = self.__head
# 循环指针找到指定的位置
while count < pos: # 1.当不满足条件退出循环时，说明指针已经指向了给定的pos位置
tail = tail.next
count += 1
tail.elem = item # 2.将pos位置的元素修改8. Delete elements
def remove(self, item):
# 删除节点
cur = self.__head # cur当前指针
pre = None # 前一个指针
while cur.next != self.__head:
# 找到了要删除的元素
if cur.elem == item:
# 要删除的元素就是第一个元素
if cur == self.__head:
tail = self.__head
# 让tail指向最后一个元素
while tail.next != self.__head:
tail = tail.next
# 删除第一个节点，改变指针的指向
tail.next = cur.next
self.__head = cur.next
else:
pre.next = cur.next
return
# 未找到要删除的元素，指针向后走，继续遍历
else:
pre = cur
cur = cur.next
# 当上面的while循环不满足条件时(cur.next == self.__head)，说明只有一个结点元素
if cur.elem == item:
if cur.next == self.__head:
pre.next = self.__head9. Find whether the element exists
def search(self, item):
# 查找节点是否存在
cur = self.__head
while cur.next != self.__head:
# 找到了返回True,未回到指向下一个继续遍历
if cur.elem == item:
return True
cur = cur.next
# 查找的元素在最后一个，遍历后指向最后一个，但是没有进入循环，所以需要在循环体外判断一次
if cur.elem == item:
return True
return False3. Complete code
class Node():
def __init__(self, elem):
# 单链表结点
self.elem = elem
self.next = None
class SingleCircleLinkList():
def __init__(self, node=None):
self.__head = node
if node:
node.next = node # 只有一个结点时，next指针指向自己，构成循环
def is_empty(self):
# 链表是否为空
if self.__head is None:
return True
else:
return False
def length(self):
# 链表长度
if self.is_empty():
return 0
count = 0
cur = self.__head
while cur.next != self.__head:
count += 1
cur = cur.next
return count
def travel(self):
# 遍历整个链表
if self.is_empty():
return
cur = self.__head
while cur.next != self.__head:
print(cur.elem, end=' ')
cur = cur.next
print(cur.elem)
def add(self, item):
# 链表头部添加元素
node = Node(item)
if self.is_empty():
self.__head = node
node.next = node
else:
tail = self.__head
# 循环找到尾结点
while tail.next != self.__head:
tail = tail.next
# 新来的节点的next指向第一个节点
node.next = self.__head
# 再改变第一个节点的指针指向新节点
self.__head = node
# 最后将尾指向指向添加node节点
tail.next = node
def append(self, item):
# 链表尾部添加元素
# 创建新结点
node = Node(item)
# 是空链表就把头节点指向这个节点
if self.is_empty():
self.__head = node
node.next = node
else:
tail = self.__head
# 找到尾节点
while tail.next != self.__head:
tail = tail.next
tail.next = node
node.next = self.__head
def modify(self, pos, item):
"""修改指定位置的元素"""
# 当指定的位置pos小于等于0时，则修改头部元素
if pos <= 0:
self.__head.elem = item
# 当pos大于等于链表总长度时，则修改尾部元素
elif pos >= self.length():
tail = self.__head
# 循环让指针指向尾部元素
while tail.next != self.__head:
tail = tail.next
tail.elem = item # 修改尾部元素
else:
count = 0
tail = self.__head
# 循环指针找到指定的位置
while count < pos: # 1.当不满足条件退出循环时，说明指针已经指向了给定的pos位置
tail = tail.next
count += 1
tail.elem = item # 2.将pos位置的元素修改
def insert(self, pos, item):
# 位置pos在第一个元素之前，则在头部插入
if pos <= 0:
self.add(item)
# 位置pos大于总长度，则在尾部插入
elif pos > self.length():
self.append(item)
else:
# 指定位置添加元素
node = Node(item)
count = 0
pre = self.__head
# 循环定位指针位置
while count < (pos-1):
count += 1
pre = pre.next
node.next = pre.next
pre.next = node
def remove(self, item):
# 删除节点
cur = self.__head # cur当前指针
pre = None # 前一个指针
while cur.next != self.__head:
# 找到了要删除的元素
if cur.elem == item:
# 要删除的元素就是第一个元素
if cur == self.__head:
tail = self.__head
# 让tail指向最后一个元素
while tail.next != self.__head:
tail = tail.next
# 删除第一个节点，改变指针的指向
tail.next = cur.next
self.__head = cur.next
else:
pre.next = cur.next
return
# 未找到要删除的元素，指针向后走，继续遍历
else:
pre = cur
cur = cur.next
# 当上面的while循环不满足条件时(cur.next == self.__head)，说明只有一个结点元素
if cur.elem == item:
if cur.next == self.__head:
pre.next = self.__head
def search(self, item):
# 查找节点是否存在
cur = self.__head
while cur.next != self.__head:
# 找到了返回True,未回到指向下一个继续遍历
if cur.elem == item:
return True
cur = cur.next
# 查找的元素在最后一个，遍历后指向最后一个，但是没有进入循环，所以需要在循环体外判断一次
if cur.elem == item:
return True
return False
if __name__ == '__main__':
ll = SingleCircleLinkList()
print(ll.is_empty())
print(ll.length())
ll.travel()
print('add')
ll.add(9)
ll.travel()
ll.add(10)
ll.travel()
print('append')
ll.append(13)
ll.travel()
print('insert')
ll.insert(5, 33)
ll.travel()
print('remove')
ll.travel()
ll.remove(10)
ll.travel()
print('modify')
ll.modify(2, 100)
ll.travel()
print(ll.search(33))