相對於單向鏈表，雙向鏈表多了一個指向前面一個節點的指針，如下圖所示：
圖片來源於網絡
利用python實現也非常的容易：
class Node(object):
def __init__(self, value):
self.value = value
self.next = None
self.prev = None
class LinkList(object):
def __init__(self):
self.head = Node('head')
def add(self, value):
p = self.head
new = Node(value)
while p.next:
p = p.next
p.next = new
new.prev = p
def remove(self, value):
p = self.head
while p.next:
if p.value == value:
temp = p.prev
xyz = p.next
temp.next = xyz
xyz.prev = temp
break
else:
p = p.next
def find(self, value):
#根據指定的值找出位置
p = self.head
i = 0
while p.next:
if p.value == value:
return i
else:
p = p.next
i += 1
raise AttributeError(u"can\'t find this element")
def index(self, index):
#根據指定的位置找出相應的值
i = 0
p = self.head
while p.next:
if i == index:
return p.value
else:
i += 1
p = p.next
raise IndexError(u'index out of range')
def findprev(self, value):
"""根據指定節點的值找出前面的一個節點的值"""
p = self.head
while 1:
if p.value == value:
return p.prev.value
break
else:
p = p.next
if not p.next:
return p.prev.value
break
raise AttributeError(u"can\'t find this element")
def findnext(self, value):
"""根據指定節點的值找出後面的一個節點的值"""
p = self.head
while 1:
if p.value == value:
return p.next.value
else:
p = p.next
if not p.next:
return None
raise AttributeError(u"can\'t find this element")
def insert(self, index, value):
"""index必須大於等於1
"""
i = 0
p = self.head
new = Node(value)
while p.next:
if i == index:
temp = p.prev
temp.next = new
new.prev = temp
new.next = p
p.prev = new
break
else:
p = p.next
i += 1
#上面循環自然結束,就直接插入到元素的末尾
else:
p.next = new
new.prev = p
def length(self):
p = self.head
i = 0
while p.next:
p = p.next
i += 1
return i
def output(self):
p = self.head
while 1:
print p.value
p = p.next
if not p.next:
print p.value
break
def reverse(self):
"""反轉鏈表"""
length = self.length()
i = 0
p = self.head.next
while p.next:
p = p.next
else:
last = p
first = self.head.next
while i < length:
first.value, last.value = last.value, first.value
first = first.next
last = last.prev
i += 1
length -= 1