leetcode-1817.js

var findingUsersActiveMinutes = function(logs, k) {
  const users = groupActionsByUser(logs)
  const uams = groupByActiveMinutes(users)

  const result = []
  for (let i=0; i < k; i++) {
    result.push(uams[i+1] || 0)
  }
  
  return result
};

function groupActionsByUser(logs) {
  const users = {}
  for (log of logs) {
    const [id, time] = log
    if (users[id]) {
      users[id].add(time)
    } else {
      users[id] = new Set([time])
    }
  }
  return users
}

function groupByActiveMinutes(users) {
  const uams = {}
  for (id in users) {
    const length = users[id].size
    if (uams[length]) {
      uams[length]++
    } else {
      uams[length] = 1
    }
  }
  return uams
}