鏈表是一種物理存儲單元上非連續、非順序的存儲結構，數據元素的邏輯順序是經過鏈表中的指針連接次序實現的。鏈表由一系列結點（鏈表中每個元素稱爲結點）組成，結點能夠在運行時動態生成。每一個結點包括兩個部分：一個是存儲數據元素的數據域，另外一個是存儲下一個結點地址的指針域。 相比於線性表順序結構，操做複雜。因爲沒必要須按順序存儲，鏈表在插入的時候能夠達到O(1)的複雜度，比另外一種線性表順序錶快得多，可是查找一個節點或者訪問特定編號的節點則須要O(n)的時間，而線性表和順序表相應的時間複雜度分別是O(logn)和O(1)。node
class Node(object):
"""
封裝節點
"""
def __init__(self, item):
# 存儲數據元素的數據域
self.item = item
# 存儲下一個結點地址的指針域
self.next = None
class Link(object):
"""
封裝鏈表
"""
def __init__(self):
# 初始化一個空鏈表
self._head = None
# '_head' 用於指向鏈表的第一個節點
def add(self, item):
"""
鏈表首部插入節點
:param item:
:return:
"""
node = Node(item)
node.next = self._head
self._head = node
def travel(self):
"""
遍歷每個節點
:return:
"""
cur = self._head
while cur:
print(cur.item)
cur = cur.next
def length(self):
"""
鏈表中節點的個數
:return:
"""
count_node = 0
cur = self._head
while cur:
count_node += 1
cur = cur.next
return count_node
def isEmpty(self):
"""
判斷鏈表是否爲空
:return:
"""
return self._head == None
def search(self, item):
"""
查找是否存在item對應的節點
:param item:
:return:
"""
find = False
cur = self._head
while cur:
if cur.item == item:
find = True
break
else:
cur = cur.next
return find
def append(self, item):
"""
鏈表的尾部插入節點
:param item:
:return:
"""
node = Node(item)
if self._head == None:
self._head = node
return
cur = self._head
pre = None
while cur:
pre = cur
cur = cur.next
pre.next = node
def insert(self, pos, item):
"""
鏈表中指定的位置插入新的節點
:param pos:
:param item:
:return:
"""
node = Node(item)
if pos == 0:
node.next = self._head
self._head = node
return
pre = None
cur = self._head
for i in range(pos):
pre = cur
cur = cur.next
pre.next = node
node.next = cur
def remove(self, item):
"""
刪除節點
:param item:
:return:
"""
cur = self._head
pre = None
if cur.item == item:
self._head = cur.next
return
while True:
pre = cur
cur = cur.next
if cur.item == item:
pre.next = cur.next
break
if cur == None:
break
def reverse(self):
"""
鏈表倒置
:return:
"""
pre = None
cur = self._head
next_node = cur.next
while cur:
cur.next = pre
pre = cur
cur = next_node
if cur != None:
next_node = next_node.next
self._head = pre
self.travel()
if __name__ == '__main__':
link = Link()
link.append(1)
link.append(2)
link.append(3)
link.append(4)
link.reverse()
# 4
# 3
# 2
# 1