python Cookbook

Posted 2021-11-30 heyaqiong

1.5 heapq模块实现一个优先级队列

#实现优先级队列
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]

    def __get__(self):#get(),set()
        return self._queue

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‘),4)
q.push(Item(‘grop‘),1)

q.pop()#bar
q.pop()#spam
q.pop()#foo
print(q.__get__())