[数据结构与算法]【Python数据结构】单链表的实现

单链表的节点实现

class SingleNode(object):
	def __init__(self,elem):
		self.elem = elem #item存放数据元素
		self.next = None #next指向下一个结点的标识

单链表的实现

class SingleLinkList(object):
	def __init__(self,node = None):
		self._head = None

	def is_empty(self):
	#判断链表是否为空
		return self._head == None
	
	def length(self):
	#返回链表长度
		cur = self._head	#cur游标，用来移动遍历节点
		count = 0 #count记录数据
		while cur != None:
			count += 1
			cur = cur.next
		return count

	def travel(self):
	#遍历整个链表
		cur = self._head
		while cur != None:
			print(cur.elem)
			cur = cur.next

	def add(self,item):
	#链表头部添加元素
		node = SingleNode(item)
		node.next = self._head
		self._head = node

	def append(self,item):
	#链表尾部添加元素
		node = SingleNode(item)
		cur = self._head
		if self.is_empty():
			self._head = node
		while cur.next != None:
			cur = cur.next
		cur.next = node

	def insert(self,pos,item):
	#指定位置添加元素
		if pos <= 0:
			self.add(item)
		elif pos > (self.length()-1):
			self.append(item)
		else:
			node = SingleNode(item)
			pre = self._head
			count = 0
			while count <= (pos-1):
				count += 1
				pre = pre.next
			node.next = pre.next
			pre.next = node

	def remove(self,item):
	#删除节点
		cur = self._head
		pre = None
		while cur != None:
			if cur.elem == item:
				if cur == self._head:
					pre.next = cur.next
					break
				else:
					pre.next = cur.next
					break
			else:
				pre = cur
				cur = cur.next

	def search(self,item):
	#查找节点是否存在
		cur = self._head
		while cur != None:
			if cur.elem == item:
				return True
			else:
				cur = cur.next
			return False