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# \*346. Moving Average from Data Stream

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

## solution

* 双端队列

```python
from collections import deque

class MovingAverage:
    def __init__(self, size: int):
        self.size = size
        self.queue = deque()
        self.sum = 0

    def next(self, val: int) -> float:
        if len(self.queue) == self.size:
            left_val = self.queue.popleft()
            self.sum -= left_val

        self.queue.append(val)
        self.sum += val
        return self.sum / len(self.queue)
```

时间复杂度：O(1)\
空间复杂度：O(n)

* 列表

```python
class MovingAverage:
    def __init__(self, size: int):
        self.size = size
        self.nums = []
        self.sum = 0

    def next(self, val: int) -> float:
        self.nums.append(val)
        self.sum += val
        if len(self.nums) > self.size:
            self.sum -= self.nums.pop(0)
        return self.sum / len(self.nums)
```

时间复杂度：O(n)\
空间复杂度：O(n)