python实现跳表SkipList的示例代码

class Node():
     def __init__(self,key,value,level):
         '''
         :param level:每个node对应的nexts层数不同
         '''
         self.key=key
         self.value=value
         self.nexts=[None]*level#节点类型next指针，初始值为空

     def __str__(self):
         #return "[key:"+str(self.key)+", value:"+str(self.value)+" len:"+str(len(self.nexts))+"]"
         return "["+str(self.key)+","+str(self.value)+","+str(len(self.nexts))+"]"

'''
跳表 Skip List ，其初衷是为了替代红黑树
'''
import random

import mkl_random
import time

class SkipList():
    def __init__(self):
        #头节点不存储任何数据
        self.MAX_LEVEL = 32  # 最大level层数
        self.__first=SkipList.Node(None, None, self.MAX_LEVEL)#头节点
        self.__level=0#实际的level层数
        self.__size=0#Jiedian个数
        self.__p=0.25#用于生成添加节点时的随机level
        return

    class Node():
        def __init__(self,key,value,level):
            '''
            :param level:每个node对应的nexts层数不同
            '''
            self.key=key
            self.value=value
            self.nexts=[None]*level

        def __str__(self):
            #return "[key:"+str(self.key)+", value:"+str(self.value)+" len:"+str(len(self.nexts))+"]"
            return "["+str(self.key)+","+str(self.value)+","+str(len(self.nexts))+"]"

    def get(self,key):
        '''
        :param key:
        :return: key对应的value
        '''
        self.keyCheck(key)
        node=self.__first
        for level in range(self.__level - 1,-1,-1):
            #在该层查找，key大于节点的key向前查找
            while node.nexts[level] and node.nexts[level].keykey:
                node=node.nexts[level]
            if node.nexts[level] and node.nexts[level].key==key:#相等则找到，否则向下寻找
                return node.nexts[level].value
        return None

    def put(self,key,value):
        '''
        return:原来的value，原来不存在key则为空
        '''
        self.keyCheck(key)
        prev=[None]*self.__level
        node=self.__first
        for i in range(self.__level - 1, -1, -1):
            while node.nexts[i] and node.nexts[i].keykey:
                node=node.nexts[i]
            if node.nexts[i] and node.nexts[i].key==key:
                oldValue=node.nexts[i].value
                node.nexts[i].value=value
                return oldValue
            prev[i]=node#保存当前level小于key的node

        newLevel=self.randomLevel()
        newNode=SkipList.Node(key,value,newLevel)
        for i in range(newLevel):
            if iself.__level:
                newNode.nexts[i]=prev[i].nexts[i]
                prev[i].nexts[i]=newNode
            else:
                self.__first.nexts[i]=newNode
        self.__size+=1
        self.__level=max(self.__level, newLevel)
        return None

    def remove(self,key):
        '''
        :return: 节点对应的value值，不存在则返回None
        '''
        self.keyCheck(key)
        prev=[None]*self.__level
        node=self.__first
        flag=False#该节点是否被查找到
        for i in range(self.__level - 1, -1, -1):
            while node.nexts[i] and node.nexts[i].keykey:
                node=node.nexts[i]
            if node.nexts[i].key==key:
                flag=True
            prev[i]=node
        if not flag:
            return None
        removedNode=node.nexts[0]#需要被删除的节点
        for i in range(len(removedNode.nexts)):#该nexts一定小于等于prev的长度
            prev[i].next[i]=removedNode.nexts[i]
        self.__size-=1
        newLevel=self.__level
        while newLevel>0 and not self.__first.nexts[newLevel - 1]:
            newLevel-=1
        self.__level=newLevel
        return removedNode.value

    def keyCheck(self, key):
        '''
        限制传入key不能为空
        '''
        if key!=0 and not key:
            raise AttributeError("key can not be None")

    def size(self):
        return self.__size

    def isEmpty(self):
        return self.__size == 0

    def randomLevel(self):#生成一个随机的层数
        level=1
        while mkl_random.rand()self.__p and levelself.MAX_LEVEL:
            level+=1
        return level

    def __str__(self):
        result=""
        for i in range(self.__level - 1, -1, -1):
            result+=str(i)
            node = self.__first
            while node.nexts[i]:
                result+=str(node.nexts[i])
                node=node.nexts[i]
            result+='\n'
        print("level:"+str(self.__level))
        return result

    def showFirst(self):
        for item in self.__first.nexts:
            print(item,end=' ')
        print()

def timeCalculate(container, size:int):
    begin=time.time()
    for i in range(size):
        if isinstance(container,dict):
            container[i]= i * 3
        else:
            container.put(i, i * 3)
    error_count = 0
    for i in range(size):
        if container.get(i) != i * 3:
            #print("wrong " + str(i) + ":" + str(skipList.get(i)))
            error_count+=1
    end=time.time()
    print(type(container))
    print(f'error rate:{float(error_count) / size:0.5f}')
    print(f'time cost:{float(end-begin)*1000:0.3f} ms')


if __name__=='__main__':
    timeCalculate({},1000000)
    timeCalculate(SkipList(),10000)