Python實現鏈表

鏈表有什么用
數組: 優點: 通過索引(數組下標)可以很快地訪問數組元素;缺點: 插入/刪除元素需要對數組進行調整, 效率低;
鏈表:優點：插入/刪除速度很快，而且不用對整個鏈表進行調整；缺點：只能進行順序訪問，不能隨機訪問（像數組一樣用下標）；
所以，鏈表在一些需要快速插入／刪除，而不太關心或者不需要隨機訪問的情況下使用
首先創建Node類

class Node:
	def __init__(self,initdata):
		self.data = initdata
		self.next = None
	def getData(self):
		return self.data
	def getNext(self):
		return self.next
	def setData(self,newdata):
		self.data = newdata
	def setNext(self,newnext):
		self.next = newnext　　

創建操作無序鏈表的類

class UnorderedList:
	def __init__(self):
		self.head = None
	def isEmpty(self):
		self.head == None
	def add(self,item):
		temp = Node(item)
		temp.setNext(self.head)
		self.head = temp
	def size(self):
		current = self.head
		count = 0
		while current != None:
			count = count + 1
			current = current.getNext()
		return count
	def search(self,item):
		current = self.head
		found = False
		while current != None and not found:
			if current.getData() == item:
				found = True
			else:
				current = current.getNext()
		return found
	def getvalue(self):
		current = self.head
		currarr = []
		while current != None:
				currarr.append(current.getData())
				current = current.getNext()
		return currarr
	def remove(self,item):
		current = self.head
		previous = None
		found = False
		while not found:
			if current.getData() == item:
				found = True
			else:
				previous = current
				current = current.getNext()
		if previous == None:
			self.head = current.getNext()
		else:
			previous.setNext(current.getNext())　

操作有序列表的類

class OrderedList:
	def __init__(self):
		self.head = None
	def size(self):
		current = self.head
		count = 0 
		while current != None:
			count = count + 1
			current = current.getNext()
		return count
	def isEmpty(self):
		return self.head == None
	def search(self,item):
		current = self.head
		found = False
		stop = False
		while current != None and not found and not stop:
			if current.getData() == item:
				found = True
			else:
				if current.getData() > item:
					stop = True
				else:
					current = current.getNext()
		return found
	def add(self,item):
		current = self.head
		previous = None
		stop = False
		while current != None and not stop:
			if current.getData() > item:
				stop = True
			else:
				previous = current
				current = current.getNext()
		temp = Node(item)
		if previous == None:
			temp.setNext(self.head)
			self.head = temp
		else:
			temp.setNext(current)
			previous.setNext(temp)