Python Cookbook 5.7 增加元素时候保持序列顺序

# -*- coding: utf-8 -*-
# [1] Python Cookbook 5.7 增加元素时候保持序列顺序
# [2] http://s99f.blog.163.com/blog/static/351183652010111602517298/

import heapq
import random

rand = random.sample(range(10), 10) # 生成随机整数列表
print rand
# >>> [7, 4, 1, 3, 8, 5, 9, 0, 2, 6]

heap = []

for x in rand:
    heapq.heappush(heap, x)

print [heapq.heappop(heap) for i in range(len(heap))]
# >>> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

# 可以用heapify函数对列表堆化
heapq.heapify(rand)
print rand
# >>> [0, 2, 1, 3, 6, 5, 9, 7, 4, 8]

# Python Cookbook 5.7节实现了一个优先级队列
class prioq:
    def __init__(self):
        self.q = []
        self.i = 0 #计数器, 如果cost一样, 则先来的元素优先级高
    def push(self, item, cost): # cost越大, 优先级越高
        heapq.heappush(self.q, (-cost, self.i, item))
        self.i += 1
    def pop(self):
        return heapq.heappop(self.q)[-1]

rand = random.sample(range(10), 10) # 生成随机整数列表
print rand
# >>> [1, 4, 3, 5, 6, 0, 7, 2, 8, 9]

q = prioq()
for i, x in enumerate(rand):
    q.push(x, i) # 用索引模拟优先级

print[ q.pop() for i in range(len(q.q))]
# >>> [9, 8, 2, 7, 0, 6, 5, 3, 4, 1]