The core values of Chinese socialism
双向链表
class Node(object):
def __init__(self, item):
self.item = item
self.next = None
self.prev = None
class DLinkList(object):
def __init__(self):
self._head = None
def is_empty(self):
return self._head == None
def length(self):
cur = self._head
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
cur = self._head
while cur != None:
print( cur.item)
cur = cur.next
def add(self, item):
node = Node(item)
if self.is_empty():
self._head = node
else:
node.next = self._head
self._head.prev = node
self._head = node
def append(self, item):
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 search(self, item):
cur = self._head
while cur != None:
if cur.item == item:
return True
cur = cur.next
return False
def insert(self, pos, item):
if pos <= 0:
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
node = Node(item)
cur = self._head
count = 0
# 移动到指定位置的前一个位置
while count < (pos - 1):
count += 1
cur = cur.next
# 将node的prev指向cur
node.prev = cur
# 将node的next指向cur的下一个节点
node.next = cur.next
# 将cur的下一个节点的prev指向node
cur.next.prev = node
# 将cur的next指向node
cur.next = node
def remove(self, item):
if self.is_empty():
return
else:
cur = self._head
if cur.item == item:
if cur.next == None:
self._head = None
else:
cur.next.prev = None
self._head = cur.next
return
while cur != None:
if cur.item == item:
cur.prev.next = cur.next
cur.next.prev = cur.prev
break
cur = cur.next
if __name__ == "__main__":
ll = DLinkList()
ll.add(1)
ll.add(2)
ll.append(3)
ll.insert(2, 4)
ll.insert(4, 5)
ll.insert(0, 6)
print( "length: ", ll.length())
ll.travel()
print( ll.search(3))
print( ll.search(4))
ll.remove(1)
print( "length:", ll.length())
ll.travel()
length: 6
6
2
1
4
3
5
True
True
length: 5
6
2
4
3
5
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