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单向链表也叫单链表,是链表中最简单的一种形式,它的每个节点包含两个域,一个信息域(元素域)和一个链接域。这个链接指向链表中的下一个节点,而最后一个节点的链接域则指向一个空值。
- 表元素域elem用来存放具体的数据。
- 链接域next用来存放下一个节点的位置(python中的标识)
- 变量p指向链表的头节点(首节点)的位置,从p出发能找到表中的任意节点。
节点实现
class SingleNode(object):
def __init__(self,item):
self.item = item # 存放数据元素
self.next = None
功能实现
class SingleLinkList(object):
def __init__(self):
self._head = None
def is_empty(self):
"""判断链表是否为空"""
return self._head == None
def length(self):
"""链表长度"""
cur = self._head
count = 0
while cur != None:
count += 1
cur = cur.next
return count
def travel(self):
"""遍历链表"""
cur = self._head
while cur != None:
print cur.item,
cur = cur.next
print ""
def add(self, item):
"""头部添加元素"""
node = SingleNode(item)
if self.is_empty():
self._head = node
else:
cur = self._head
while cur.next != None:
cur = cur.next
cur.next = node
def insert(self, pos, item):
if pos <= 0:
self.add(item)
elif pos > (self.length() - 1):
self.append(item)
else:
node = SingNode(item)
count = 0
pre = self._head
while count < (pos-1):
count += 1
pre = pre.next
node.next = pre.next
def remove(self, item):
"""删除节点"""
cur = self._head
pre = None
while cur != Node:
if cur.item == item:
if not pre:
self._head = cur.next
else:
pre.next = cur.next
break
else:
pre = cur
cur = cur.next
def search(self, item):
cur = self._head
while cur != None:
if cur.item == item:
return True
cur = cur.next
return False
操作测试
if __name__ == "__main__":
ll = SingleLinkList()
ll.add(1)
ll.add(2)
ll.append(3)
ll.insert(2, 4)
print "length:",ll.length()
ll.travel()
print ll.search(3)
print ll.search(5)
ll.remove(1)
print "length:",ll.length()
ll.travel()