Leetcode 346. Moving Average from Data Stream

Posted 2020-08-29 lettuan

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window.

For example,

MovingAverage m = new MovingAverage(3);
m.next(1) = 1
m.next(10) = (1 + 10) / 2
m.next(3) = (1 + 10 + 3) / 3
m.next(5) = (10 + 3 + 5) / 3

 

思路：本题比较简单，在__init__的时候，先构造一个stack = []。然后逐个往里面push元素，如果长度达到window size了，需要先pop最上面的一个元素。

 1 class MovingAverage(object):
 2 
 3     def __init__(self, size):
 4         """
 5         Initialize your data structure here.
 6         :type size: int
 7         """
 8         self.win_size = size
 9         self.stack = []
10         
11 
12     def next(self, val):
13         """
14         :type val: int
15         :rtype: float
16         """
17         if len(self.stack) < self.win_size:
18             self.stack.append(float(val))
19             return sum(self.stack)/len(self.stack)
20         else:
21             self.stack.pop(0)
22             self.stack.append(float(val))
23             return float(sum(self.stack)/len(self.stack))