#! /usr/bin/env python
#coding=utf-8

class Queue(object):
    def __init__(self,size):
        self.size=size
        self.head=-1 #初始化队头
        self.tail=-1 #初始化队尾
        self.queue=[]

    def EnQueue(self,x):
        if self.IsFull():#如果试图往满队列插入元素，则发生上溢
            raise Exception("overflow !")
        else:
            self.queue.append(x)
            self.tail += 1 #往队列中加入元素是在尾部进行

    def DeQueue(self):
        if self.IsEmpty():#如果试图从空队列删除元素，则发生下溢
            raise Exception("underflow !")
        else:
            self.head += 1#从队列中删除元素在队头进行，将队头后移
            return self.queue.pop(0)#利用内建函数pop()将队头弹出

    def IsFull(self):#判断队列满
        #return (self.tail+1)%self.size == self.head
        return self.tail-self.head+1==self.size
    def IsEmpty(self):#判断队列空！！！
        return self.head == self.tail

if __name__ == '__main__':
    q=Queue(10)
    for i in range(3):
        q.EnQueue(i)
    print q.queue
    print q.DeQueue()
    print q.queue
    print q.DeQueue()
    print q.IsEmpty()
    print q.DeQueue()
    print q.IsEmpty()
    print q.queue
    for i in range(9):
        q.EnQueue(i)
    print q.queue
    print q.IsFull()