# coding=utf-8

# example.py

#

# Example of a priority queue

import heapq

class PriorityQueue:

    def __init__(self):

        self._queue = []

        self._index = 0

    def push(self, item, priority):

        heapq.heappush(self._queue, (-priority, self._index, item)) #在这里就是依据优先级的负数作排序依据，最小的在左边，是第0个值

        self._index += 1    #当优先级一样是，index按照小的先输出，保证了先进先出

    def pop(self):

        return heapq.heappop(self._queue)[-1]   #返回item

# Example use

class Item:

    def __init__(self, name):

        self.name = name

    def __repr__(self):

        return 'Item({!r})'.format(self.name)#！后面可以加s r分别对应str() repr() ,和%用法类似，s没括号，r有括号

q = PriorityQueue()

q.push(Item('foo'), 1)

q.push(Item('bar'), 5)

q.push(Item('spam'), 4)

q.push(Item('grok'), 1)

print("Should be bar:", q.pop())

print("Should be spam:", q.pop())

print("Should be foo:", q.pop())

print("Should be grok:", q.pop())

a=[5,8,9]

b=[5,1,2]

c=[4,6,7]

ss=[]

heapq.heappush(ss,a)#是按照a中序列的第一个作排序依据的

heapq.heappush(ss,b)

heapq.heappush(ss,c)

print ss

s=heapq.heappop(ss)[-1]

print s,ss

s=heapq.heappop(ss)[-1]

print s,ss

s=heapq.heappop(ss)[-1]

print s,ss