单链表，双向链表，单向循环链表python定义以及基础操作的实现
python和其他很多语言的不同之处在于python中的变量名是有实际意义的如：
a = 10
a保存的是存储10这个数值的空间的地址也称为引用
而对于C
a这个变量名就是一个代号，他不占内存。具体的c中变量名的意义可以参考：https://blog.csdn.net/CSDN_LSD/article/details/78572491
由于pythond的这个特性，python实现链表以及链表的基本操作要简单一些。
代码如下：
单链表
class Node(object):
"""定义一个节点"""
def __init__(self, elem):
self.elem = elem
self.next = None
class SingleLinkList(object):
"""单链表"""
def __init__(self, node=None):
# 因为不需要让用户知道我的头结点在哪里所以head定义为私有的属性。
self.__head = node
def is_empty(self):
"""链表是否为空"""
return self.__head is None
def length(self):
"""链表的长度"""
# cur游标，用来移动遍历节点
cur = self.__head
# count记录数量
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历整个链表"""
cur = self.__head
while cur != None:
print(cur.elem, end=" ")
cur = cur.next
print("")
def add(self, item):
"""链表头部添加元素"""
node = Node(item)
node.next = self.__head
self.__head = node
def append(self, item):
"""链表尾部添加元素"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
# pos/position:位置，方位 param:参数
def insert(self, pos, item):
"""指定位置添加元素
:param pos 从0开始(即将链表的第一个节点记为0节点)"""
# pre/previous以前的，在什么之前
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
node = Node(item)
pre = self.__head
count = 0
while count < (pos-1):
count += 1
pre = pre.next
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除节点"""
pre = self.__head
# 判断是不是空链表
if pre == None:
return False
# 判断是不是头结点，包含了只有一个节点情况
elif pre.elem == item:
self.__head = pre.next
# pre = None
return True
else:
while pre.next != None:
if pre.next.elem == item:
pre.next = pre.next.next
return True
else:
pre = pre.next
return False
# 也可以使用这种方法
# cur = self.__head
# pre = None
# while cur != None:
# if cur.elem == item:
# # 先判断此结点是否是头节点
# # 头节点
# if cur == self.__head:
# self.__head = cur.next
# else:
# pre.next = cur.next
# break
# else:
# pre = cur
# cur = cur.next
def search(self, item):
"""查找节点是否存在"""
cur = self.__head
while cur != None:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == '__main__':
sll = SingleLinkList()
print(sll.remove(4))
sll.travel()
print("----------")
sll.append(2)
print(sll.search(2))
print(sll.remove(2))
print("----------")
sll.append(2)
sll.append(3)
sll.append(5)
sll.append(6)
sll.append(7)
sll.travel()
sll.add(1)
sll.travel()
sll.insert(3, 4)
sll.travel()
sll.remove(1)
sll.travel()
sll.remove(7)
sll.travel()
sll.remove(4)
sll.travel()
print(sll.remove(100))
sll.travel()
print(sll.search(6))双向链表
class Node(object):
"""节点"""
def __init__(self, item):
self.elem = item
self.next = None
self.prev = None
class DoubleLinkList(object):
"""双向链表"""
def __init__(self, node=None):
self.__head = node
def is_empty(self):
"""链表是否为空"""
return self.__head is None
def length(self):
"""链表长度"""
# cur游标，用来移动遍历节点
cur = self.__head
# counter:记录数量
counter = 0
while cur != None:
counter += 1
cur = cur.next
return counter
def append(self, item):
"""链表尾部添加节点，尾插法"""
node = Node(item)
if self.is_empty():
self.__head = node
else:
cur = self.__head
while cur.next != None:
cur = cur.next
cur.next = node
node.prev = cur
def add(self, item):
"""链表头部添加节点，头插法"""
node = Node(item)
node.next = self.__head
self.__head = node
node.next.prev = node
def insert(self, pos, item):
"""任意位置添加节点"""
# pos的初始值为0
if pos <= 0:
self.add()
elif pos > (self.length()-1):
self.append()
else:
cur = self.__head
counter = 0
while counter != pos:
counter += 1
cur = cur.next
node = Node(item)
node.prev = cur.prev
cur.prev.next = node
node.next = cur
cur.prev = node
def travel(self):
"""遍历整个链表"""
cur = self.__head
while cur != None:
print(cur.elem, end=" ")
cur = cur.next
print("")
def remove(self, item):
"""根据元素删除节点"""
cur = self.__head
while cur != None:
if cur.elem == item:
# 先判断此结点是否是头节点
# 头节点
if cur == self.__head:
self.__head = cur.next
if cur.next != None:
# 链表不只有一个节点
cur.next.prev = None
else:
cur.prev.next = cur.next
if cur.next != None:
cur.next.prev = cur.prev
return True
else:
cur = cur.next
return False
def search(self, item):
"""根据元素查找节点是否存在"""
cur = self.__head
while cur != None:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == '__main__':
dll = DoubleLinkList()
print(dll.remove(4))
dll.travel()
print("----------")
dll.append(2)
print(dll.search(2))
print(dll.remove(2))
print("----------")
dll.append(2)
dll.append(3)
dll.append(5)
dll.append(6)
dll.append(7)
dll.travel()
dll.add(1)
dll.travel()
dll.insert(3, 4)
dll.travel()
dll.remove(1)
dll.travel()
dll.remove(7)
dll.travel()
dll.remove(4)
dll.travel()
print(dll.remove(100))
dll.travel()单向循环链表
class Node(object):
"""定义一个节点"""
def __init__(self, elem):
self.elem = elem
self.next = None
class SingleLinkList(object):
"""单向循环链表"""
def __init__(self, node=None):
# 因为不需要让用户知道我的头结点在哪里所以head定义为私有的属性。
self.__head = node
if node != None:
node.next = node
def is_empty(self):
"""链表是否为空"""
return self.__head is None
def length(self):
"""链表的长度"""
if self.is_empty():
return 0
# cur游标，用来移动遍历节点
cur = self.__head
# count记录数量,因为循环不会进入最后一个节点所以初始值为1
count = 1
while cur.next != self.__head:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历整个链表"""
cur = self.__head
if cur == None:
return
else:
while cur.next != self.__head:
print(cur.elem, end=" ")
cur = cur.next
# 退出循环后cur指向尾节点，但是尾节点没有打印。
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 = self.__head
# 或者
# self.__head = node
# node.next = node
else:
cur = self.__head
while cur.next != self.__head:
cur = cur.next
# 循环结束后cur指向尾节点
node.next = self.__head
self.__head = node
cur.next = node
def append(self, item):
"""链表尾部添加元素"""
node = Node(item)
if self.is_empty():
self.__head = node
node.next = node
else:
cur = self.__head
while cur.next != self.__head:
cur = cur.next
# 循环结束cur指向最后一个节点
cur.next = node
node.next = self.__head
# pos/position:位置，方位 param:参数
def insert(self, pos, item):
"""指定位置添加元素
:param pos 从0开始(即将链表的第一个节点记为0节点)"""
# pre/previous以前的，在什么之前
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
node = Node(item)
pre = self.__head
count = 0
while count < (pos-1):
count += 1
pre = pre.next
node.next = pre.next
pre.next = node
def remove(self, item):
"""删除节点"""
pre = self.__head
cur = self.__head
# 判断是不是空链表
if cur == None:
return False
# 判断是不是头结点
elif cur.elem == item:
# 判断是不是只有一个节点
if cur.next == self.__head:
self.__head = None
return True
else:
while pre.next != self.__head:
pre = pre.next
self.__head = cur.next
pre.next = self.__head
return True
else:
while pre.next != self.__head:
if pre.next.elem == item:
pre.next = pre.next.next
return True
else:
pre = pre.next
return False
def search(self, item):
"""查找节点是否存在"""
cur = self.__head
# 判断是否为空链表
if self.__head == None:
return False
# 判断是不是头结点
elif cur.elem == item:
return True
else:
while cur.next != self.__head:
if cur.elem == item:
return True
else:
cur = cur.next
# 循环退出后cur指向最后一个节点，但是没有进入最后一个节点
if cur.elem == item:
return True
return False
if __name__ == '__main__':
sll = SingleLinkList()
print(sll.remove(4))
sll.travel()
print("----------")
sll.append(2)
print(sll.search(2))
print(sll.remove(2))
print("----------")
sll.append(2)
sll.append(3)
sll.append(5)
sll.append(6)
sll.append(7)
sll.travel()
sll.add(1)
sll.travel()
sll.insert(3, 4)
sll.travel()
sll.remove(1)
sll.travel()
sll.remove(7)
sll.travel()
sll.remove(4)
sll.travel()
print(sll.remove(100))
sll.travel()
print(sll.search(6))