1817-finding-the-users-active-minutes.js

/**
 * 1817. Finding the Users Active Minutes
 * https://leetcode.com/problems/finding-the-users-active-minutes/
 * Difficulty: Medium
 *
 * You are given the logs for users' actions on LeetCode, and an integer k. The logs are represented
 * by a 2D integer array logs where each logs[i] = [IDi, timei] indicates that the user with IDi
 * performed an action at the minute timei.
 *
 * Multiple users can perform actions simultaneously, and a single user can perform multiple actions
 * in the same minute.
 *
 * The user active minutes (UAM) for a given user is defined as the number of unique minutes in which
 * the user performed an action on LeetCode. A minute can only be counted once, even if multiple actions
 * occur during it.
 *
 * You are to calculate a 1-indexed array answer of size k such that, for each j (1 <= j <= k), answer[j]
 * is the number of users whose UAM equals j.
 *
 * Return the array answer as described above.
 */

/**
 * @param {number[][]} logs
 * @param {number} k
 * @return {number[]}
 */
var findingUsersActiveMinutes = function(logs, k) {
  const map = new Map();
  logs.forEach(([id, time]) => {
    map.set(id, map.get(id) || new Set());
    map.get(id).add(time);
  });

  const result = new Array(k).fill(0);
  [...map.values()].forEach(({ size }) => result[size - 1]++);

  return result;
};