public class Solution
extends Object
2244 - Minimum Rounds to Complete All Tasks\.
Medium
You are given a **0-indexed** integer array `tasks`, where `tasks[i]` represents the difficulty level of a task. In each round, you can complete either 2 or 3 tasks of the **same difficulty level**.
Return _the **minimum** rounds required to complete all the tasks, or_ `-1` _if it is not possible to complete all the tasks._
**Example 1:**
**Input:** tasks = [2,2,3,3,2,4,4,4,4,4]
**Output:** 4
**Explanation:** To complete all the tasks, a possible plan is:
- In the first round, you complete 3 tasks of difficulty level 2.
- In the second round, you complete 2 tasks of difficulty level 3.
- In the third round, you complete 3 tasks of difficulty level 4.
- In the fourth round, you complete 2 tasks of difficulty level 4.
It can be shown that all the tasks cannot be completed in fewer than 4 rounds, so the answer is 4.
**Example 2:**
**Input:** tasks = [2,3,3]
**Output:** -1
**Explanation:** There is only 1 task of difficulty level 2, but in each round, you can only complete either 2 or 3 tasks of the same difficulty level. Hence, you cannot complete all the tasks, and the answer is -1.
**Constraints:**
* 1 <= tasks.length <= 105
* 1 <= tasks[i] <= 109