Moving Average from Data Stream

Description

null

Solution(javascript)

// /** 1: 直接往后加, 空间没有优化
//  * Initialize your data structure here.
//  * @param {number} size
//  */
// const MovingAverage = function (size) {
//   this.size = size
//   this.sum = 0
//   this.queue = []
//   this.front = 0
// }

// /**
//  * @param {number} val
//  * @return {number}
//  */
// MovingAverage.prototype.next = function (val) {
//   this.queue.push(val)
//   this.sum += val
//   if (this.queue.length - this.front > this.size) {
//     this.sum -= this.queue[this.front++]
//   }
//   return this.sum / (this.queue.length - this.front)
// }


/** 2: 空间优化
 * Initialize your data structure here.
 * @param {number} size
 */
const MovingAverage = function (size) {
  this.size = size
  this.sum = 0
  this.queue = new Array(size).fill(0)
  this.index = 0
}

/**
 * @param {number} val
 * @return {number}
 */
MovingAverage.prototype.next = function (val) {
  const currentIndex = (this.index++) % this.size
  this.sum += val - this.queue[currentIndex]
  this.queue[currentIndex] = val

  return this.sum / Math.min(this.index, this.size)
}