滑动窗口的平均值

题目

给定一个整数数据流和一个窗口大小, 根据该滑动窗口的大小, 计算滑动窗口里所有数字的平均值.

实现 MovingAverage 类:

MovingAverage(int size) 用窗口大小 size 初始化对象. double next(int val) 成员函数 next 每次调用的时候都会往滑动窗口增加一个整数, 请计算并返回数据流中最后 size 个值的移动平均值, 即滑动窗口里所有数字的平均值.

示例

输入: 
inputs = ["MovingAverage", "next", "next", "next", "next"]
inputs = [[3], [1], [10], [3], [5]]

输出: [null, 1.0, 5.5, 4.66667, 6.0]

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

题解

没啥可说的, 太简单了.

JavaScript

/**
 * Initialize your data structure here.
 * @param {number} size
 */
var MovingAverage = function (size) {
  this.size = size
  this.queue = []
}

/**
 * @param {number} val
 * @return {number}
 */
MovingAverage.prototype.next = function (val) {
  if (this.queue.length === this.size) {
    this.queue.shift()
  }

  this.queue.push(val)

  return this.queue.reduce((acc, val) => acc + val, 0) / this.queue.length
}

/**
 * Your MovingAverage object will be instantiated and called as such:
 * var obj = new MovingAverage(size)
 * var param_1 = obj.next(val)
 */

Rust

struct MovingAverage {
    queue: Vec<i32>,
    size: i32,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl MovingAverage {
    /** Initialize your data structure here. */
    fn new(size: i32) -> Self {
        MovingAverage {
            queue: Vec::with_capacity(size as usize),
            size,
        }
    }

    fn next(&mut self, val: i32) -> f64 {
        if self.queue.len() == self.size as usize {
            self.queue.remove(0);
        }

        self.queue.push(val);
        self.queue.iter().sum::<i32>() as f64 / self.queue.len() as f64
    }
}

/**
 * Your MovingAverage object will be instantiated and called as such:
 * let obj = MovingAverage::new(size);
 * let ret_1: f64 = obj.next(val);
  */