LeetCode 346. Moving Average from Data Stream

Description

https://leetcode.com/problems/moving-average-from-data-stream/

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

Implement the MovingAverage class:

• MovingAverage(int size) Initializes the object with the size of the window size.
• double next(int val) Returns the moving average of the last size values of the stream.

Example 1:

Input
["MovingAverage", "next", "next", "next", "next"]
[, , , , ]
Output

[null, 1.0, 5.5, 4.66667, 6.0]

Explanation MovingAverage movingAverage = new MovingAverage(3); movingAverage.next(1); // return 1.0 = 1 / 1 movingAverage.next(10); // return 5.5 = (1 + 10) / 2 movingAverage.next(3); // return 4.66667 = (1 + 10 + 3) / 3 movingAverage.next(5); // return 6.0 = (10 + 3 + 5) / 3

Constraints:

• 1 <= size <= 1000
• -105 <= val <= 105
• At most 104 calls will be made to next.

Explanation

Track the numbers added and size of numbers.

Python Solution

class MovingAverage:

def __init__(self, size: int):
"""
"""
self.numbers = []
self.size = size

def next(self, val: int) -> float:
self.numbers.append(val)

if len(self.numbers) > self.size:
return sum(self.numbers[-(self.size):]) / self.size

return sum(self.numbers) / len(self.numbers)

# Your MovingAverage object will be instantiated and called as such:
# obj = MovingAverage(size)
# param_1 = obj.next(val)
• Time Complexity: O(N).
• Space Complexity: O(N).