# coding:utf-8
class Node(object):
"""結點"""
def __init__(self, item):
self.elem = item
self.next = None
self.prev = None
class DoubleLinkList(object):
"""雙向鏈表"""
def __init__(self, node=None):
self.__head = node
def is_empty(self):
"""鏈表是否爲空"""
return self.__head == None
def length(self):
"""鏈表長度"""
#cur遊樸，用來移動遍歷節點
cur = self.__head
#count記錄數量
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍歷整個鏈表"""
cur = self.__head
while cur != None:
print(cur.elem, end=" ")
cur = cur.next
print("")
def add(self, item):
"""鏈表頭部添加元素,頭插法"""
node = Node(item)
node.next = self.__head
self.__head = node
node.next.prev = node
def append(self, item):
"""鏈表尾部添加元素，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 insert(self, pos, item):
"""指定位置添加元素
：param pos 從0開始
"""
if pos <= 0:
self.add(item)
elif pos > (self.length()-1):
self.append(item)
else:
cur = self.__head
count = 0
while count < pos:
count += 1
cur = cur.next
# 當循環退出後，cur指向pos位置
node = Node(item)
node.next = cur
node.prev = cur.prev
cur.prev.next = node
cur.prev = node
def remove(self, item):
"""刪除節點"""
cur = self.__head
while cur != None:
if cur.elem == item:
# 先判斷此結點是否是頭節點
# 頭節點
if cur == self.__head:
self.__head = cur.next
if cur.next:
# 判斷鏈表是否只有一個結點
cur.next.prev = None
else:
cur.prev.next = cur.next
if cur.next:
cur.next.prev = cur.prev
break
else:
cur = cur.next
def search(self, item):
"""查找節點是否存在"""
cur = self.__head
while cur != None:
if cur.elem == item:
return True
else:
cur = cur.next
return False
if __name__ == "__main__":
ll = DoubleLinkList()
print(ll.is_empty())
print(ll.length())
ll.append(1)
print(ll.is_empty())
print(ll.length())
ll.append(2)
ll.add(8)
ll.append(3)
ll.append(4)
ll.append(5)
ll.append(6)
# 8 1 2 3 4 5 6
ll.insert(-1, 9) # 9 8 123456
ll.travel()
ll.insert(3, 100) # 9 8 1 100 2 3456
ll.travel()
ll.insert(10, 200) # 9 8 1 100 23456 200
ll.travel()
ll.remove(100)
ll.travel()
ll.remove(9)
ll.travel()
ll.remove(200)
ll.travel()
执行结果
