def pop(self):
if self._head is None:
raise LinkedListUnderflow("in pop of DLList")
e = self._head.elem
self._head = self._head.next
if self._head:
self._head = None
return e
def pop(self):
if self._rear is None:
raise LinkedListUnderflow("in pop of LCList")
p = self._rear.next
if self._rear is p:
self._rear = None
else:
self._rear.next = p.next
return p.elem
def pop_last(self):
if self._head is None:
raise LinkedListUnderflow("in pop_last of DLList")
e = self._rear.elem
self._rear = self._rear.prev
if self._rear is None:
self._head = None
else:
self._rear.next = None
return e
def pop(self):
# 如果是空表
if self._head is None:
raise LinkedListUnderflow('空表')
# 保存被删除的元素
e = self._head.elem
# 让链表的头指针指向第二个结点
self._head = self._head.next
if self._head is not None:
# 把第二个结点的prev指针设为空
self._head.prev = None
return e
def insert(self, elem, i=0):
p = self._head
if i == 0:
if self._head is None:
self._head = LNode(elem, self._head)
self._rear = self._head
else:
self._head = LNode(elem, self._head)
return
elif i != 0 and self._head is None:
raise LinkedListUnderflow("insert")
elif self.length() < i or i < 0:
raise LinkedListUnderflow("insert length error")
else:
pass
while p is not None and (i - 1) > 0:
i -= 1
p = p.next
p.next = LNode(elem, p.next)
self._rear = p.next
def pop(self):
# 如果是空表
if self._head is None:
raise LinkedListUnderflow('该表中没有元素')
# 不是空表
# 如果只有一个元素，则头指针和尾指针都指向None
elif self._head.next == None:
self._head = self._head.next
self._rear = self._head
# 不只一个元素，丢弃第一个结点
else:
self._head = self._head.next
def pop(self):
# 如果是空表
if self._rear is None:
raise LinkedListUnderflow('空表')
# p保存要弹出的结点
p = self._rear.next
# 如果只有一个结点
if self._rear is p:
self._rear = None
else:
self._rear.next = p.next
# 返回要删除的元素
return p.elem
def deltail(self):
if self._head is None:
raise LinkedListUnderflow('空表')
e = self._rear.elem
# 让表尾指针指向倒数第二个结点
self._rear = self._rear.prev
# 如果删除了一个结点后，没有结点了
if self._rear is None:
self._head = None
else:
# 把倒数第二个结点的next设为None
self._rear.next = None
return e
def pop_last(self):
if self._head is Node:
raise LinkedListUnderflow("in pop_last")
p = self._head
if p.next is None:
e = p.elem
self._head = None
return e
while p.next.next:
p = p.next
e = p.next.elem
p.next = None
self._rear = p
def deltail(self):
# 如果是空表
if self._rear is None:
raise LinkedListUnderflow('空表')
# 扫面指针，从头开始
p = self._rear.next
if self._rear is p:
self._rear = None
else:
while p.next.next is not self._rear.next:
p = p.next
# return p.next.elem
p.next = self._rear.next
self._rear = p
def pop_last(self):
if self.is_empty():
raise LinkedListUnderflow("in pop_last")
p = self._rear.next
if p is self._rear:
self._rear = None
return p.elem
else:
e = self._rear.elem
while True:
if p.next is self._rear:
break
p = p.next
p.next = self._rear.next
self._rear = p
return e
def deltail(self):
# 如果是空表
if self._head is None:
raise LinkedListUnderflow('该表中没有元素')
# 扫描指针
p = self._head
# 表中只有一个元素
if self._head.next is None:
e = p.elem
self._head = None
return e
# 找到最后一个结点
while p.next.next is not None:
p = p.next
e = p.next.elem
p.next = None
self._rear = p
return e