LeetCode: Longest Harmonious Subsequence Solution

Approach

As the sequence only the max and the min whose diff is 1

Use the hash table for element and its occurence

Implementation

1/**
2 * @param {number[]} nums
3 * @return {number}
4 */
5var findLHS = function (nums) {
6  const elOccMap = nums.reduce(
7    (acc, el) => acc.set(el, (acc.get(el) || 0) + 1),
8    new Map()
9  )
10  let max = 0
11  for (const [el, occ] of elOccMap) {
12    if (elOccMap.get(el + 1)) {
13      max = Math.max(max, occ + elOccMap.get(el + 1))
14    }
15  }
16  return max
17}