[PY3]——实现一个优先级队列

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))
        self._index+=1

    def pop(self):
        return heapq.heappop(self._queue)[-1]

class Item:
    def __init__(self,name):
        self.name=name
    def __repr__(self):
        return ‘Item({!r})‘.format(self.name)

q=PriorityQueue()
q.push(Item(‘foo‘),1)
q.push(Item(‘bar‘),5)
q.push(Item(‘spam‘),2)
q.push(Item(‘grok‘),1)

print(q.pop())
print(q.pop())
print(q.pop())
print(q.pop())

   Item(‘bar‘)
   Item(‘spam‘)
   Item(‘foo‘)
   Item(‘grok‘)