单链表的Python实现
# 结点类
class Node:
def __init__(self, value):
self.value = value
self.next = None
# 单链表
class SingleLinklist:
def __init__(self, node=None):
# 头结点定义为私有变量
self._head = node
def is_empty(self):
# 判断链表是否为空
if self._head is None:
return True
else:
return False
def length(self):
# 返回链表的长度
# cur游标，用来移动遍历结点
# count用来计数
cur = self._head
count = 0
while cur:
count += 1
cur = cur.next
return count
def travel(self):
# 遍历输出整个链表
cur = self._head
while cur:
print(cur.value, end=' ')
cur = cur.next
print()
def add(self, item):
# 头部添加一个结点
node = Node(item)
if self._head is None:
self._head = node
else:
node.next = self._head
self._head = node
def append(self, item):
# 尾部添加一个结点
node = Node(item)
# 若链表为空，直接将该结点作为链表的第一个元素
if self._head is None:
self._head = node
else:
cur = self._head
while cur.next is not None:
cur = cur.next
cur.next = node
def insert(self, pos, item):
# 在指定位置pos添加结点
# 若指定位置pos为第一个元素之前，则执行头部插入
if pos <= 0:
self.add(item)
# 若指定位置超过链表尾部，则执行尾部插入
elif pos > self.length():
self.append(item)
else:
pre = self._head
count = 0
node = Node(item)
while count < pos - 1:
count += 1
pre = pre.next
node.next = pre.next
pre.next = node
def remove(self, item):
# 删除一个结点
# 若链表为空，则直接返回
if self.is_empty():
return
pre = None
cur = self._head
while cur:
# 若没有找到元素，继续按链表后移结点
if cur.value != item:
pre = cur
cur = cur.next
else:
# 若要删除的点为头结点
if cur == self._head:
self._head = cur.next
break
else:
pre.next = cur.next
break
def search(self, item):
# 查找结点是否存在
cur = self._head
while cur:
if cur.value == item:
return True
else:
cur = cur.next
return False
if __name__ == '__main__':
slink = SingleLinklist()
print(slink.is_empty())
print(slink.length())
slink.append(1)
slink.append(2)
slink.append(3)
slink.append(4)
slink.travel()
slink.insert(2, 9)
slink.travel()
slink.remove(1)
slink.travel()
