347. Top K Frequent Elements

Link: https://leetcode.com/problems/top-k-frequent-elements

Description: We need to find k most frequent elements in array.

Solution:

Create object and count how many times each number appears in array. Then sort object by values and return first k keys.

var topKFrequent = function (nums, k) {
  const obj = {}

  for (const n of nums) {
    if (obj[n] !== undefined) {
      obj[n] += 1
      continue
    }
    obj[n] = 1
  }
  const sorted = Object.entries(obj).sort((a, b) => {
    if (a[1] < b[1]) {
      return 1
    } else {
      return -1
    }
  })

  return sorted.slice(0, k).map((el) => +el[0])
}