class Queue(object):"""队列"""def __init__(self):self.items = []def is_empty(self):return self.items == []def enqueue(self, item):"""进队列"""self.items.insert(0,item)def dequeue(self):"""出队列"""return self.items.pop()def size(self):"""返回大小"""return len(self.items)if __name__ == "__main__":q = Queue()q.enqueue("hello")q.enqueue("world")q.enqueue("itcast")print q.size()print q.dequeue()print q.dequeue()print q.dequeue()

from pythonds.basic.queue import Queuedef hotPotato(namelist, num):simqueue = Queue()for name in namelist:simqueue.enqueue(name)while simqueue.size() > 1:for i in range(num):simqueue.enqueue(simqueue.dequeue())simqueue.dequeue()return simqueue.dequeue()print(hotPotato(["Bill","David","Susan","Jane","Kent","Brad"],7))

# 模拟打印机
class Printer:def __init__(self, ppm):self.pagerate = ppmself.currentTask = Noneself.timeRemaining = 0def tick(self):if self.currentTask != None:self.timeRemaining = self.timeRemaining - 1if self.timeRemaining <= 0:self.currentTask = Nonedef busy(self):if self.currentTask != None:return Trueelse:return Falsedef startNext(self,newtask):self.currentTask = newtaskself.timeRemaining = newtask.getPages() * 60/self.pagerate# 模拟任务
import randomclass Task:def __init__(self,time):self.timestamp = timeself.pages = random.randrange(1,21)def getStamp(self):return self.timestampdef getPages(self):return self.pagesdef waitTime(self, currenttime):return currenttime - self.timestamp#模拟打印机任务队列
from pythonds.basic.queue import Queueimport randomdef simulation(numSeconds, pagesPerMinute):labprinter = Printer(pagesPerMinute)printQueue = Queue()waitingtimes = []for currentSecond in range(numSeconds):if newPrintTask():task = Task(currentSecond)printQueue.enqueue(task)if (not labprinter.busy()) and (not printQueue.isEmpty()):nexttask = printQueue.dequeue()waitingtimes.append(nexttask.waitTime(currentSecond))labprinter.startNext(nexttask)labprinter.tick()averageWait=sum(waitingtimes)/len(waitingtimes)print("Average Wait %6.2f secs %3d tasks remaining."%(averageWait,printQueue.size()))def newPrintTask():num = random.randrange(1,181)if num == 180:return Trueelse:return Falsefor i in range(10):simulation(3600,5)