LeetCode: Maximum Frequency Stack Solution

1var FreqStack = function () {
2  this.freqMap = new Map()
3  this.freqWithElsArr = []
4  this.mostFreq = 0
5}
6
7/**
8 * @param {number} x
9 * @return {void}
10 */
11FreqStack.prototype.push = function (x) {
12  const freq = (this.freqMap.get(x) || 0) + 1
13  if (!this.freqWithElsArr[freq]) {
14    this.freqWithElsArr[freq] = []
15  }
16
17  this.freqWithElsArr[freq].push(x)
18  this.freqMap.set(x, freq)
19  this.mostFreq = Math.max(this.mostFreq, freq)
20
21  return null
22}
23
24/**
25 * @return {number}
26 */
27FreqStack.prototype.pop = function () {
28  const x = this.freqWithElsArr[this.mostFreq].pop()
29
30  if (this.freqWithElsArr[this.mostFreq].length === 0) {
31    this.mostFreq--
32  }
33
34  this.freqMap.set(x, this.freqMap.get(x) - 1)
35
36  return x
37}
38
39/**
40 * Your FreqStack object will be instantiated and called as such:
41 * var obj = new FreqStack()
42 * obj.push(x)
43 * var param_2 = obj.pop()
44 */