数据结构：优先队列 基于list实现（python版）

 #!/usr/bin/env python
 # -*- coding:utf-8 -*-

 #Author: Minion-Xu
 #list实现优先队列

 class ListPriQueueValueError(ValueError):
     pass

 class List_Pri_Queue(object):
     def __init__(self, elems = []):
         self._elems = list(elems)
         #从大到小排序，末尾值最小，但优先级最高，方便弹出且效率为O（1）
         self._elems.sort(reverse=True)

     #判断队列是否为空
     def is_empty(self):
         return self._elems is []

     #查看最高优先级 O(1)
     def peek(self):
         if self.is_empty():
             raise ListPriQueueValueError("in pop")
         return self._elems[-1]

     #弹出最高优先级 O(1)
     def dequeue(self):
         if self.is_empty():
             raise ListPriQueueValueError("in pop")
         return self._elems.pop()

     #入队新的优先级 O(n)
     def enqueue(self, e):
         i = len(self._elems) - 1
         while i>=0:
             if self._elems[i] < e:
                 i -= 1
             else:
                 break
         self._elems.insert(i+1, e)

 if __name__=="__main__":
     l = List_Pri_Queue([4,6,1,3,9,7,2,8])
     print(l._elems)
     print(l.peek())
     l.dequeue()
     print(l._elems)
     l.enqueue(5)
     print(l._elems)
     l.enqueue(1)
     print(l._elems)