Task Scheduler
Difficulty: Medium
Category: DSA
Topics: Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Counting
Asked at: Facebook, Rubrik, Amazon, Pinterest, Google, Microsoft, Bloomberg, Airtel
You are given an array of CPU `tasks`, each labeled with a letter from A to Z, and a number `n`. Each CPU interval can be idle or allow the completion of one task. Tasks can be completed in any order, but there's a constraint: there has to be a gap of **at least** `n` intervals between two tasks with the same label.
Return the **minimum** number of CPU intervals required to complete all tasks.
**Example 1:**
**Input:** tasks = ["A","A","A","B","B","B"], n = 2
**Output:** 8
**Explanation:** A possible sequence is: A -> B -> idle -> A -> B -> idle -> A -> B.
After completing task A, you must wait two intervals before doing A again. The same applies to task B. In the 3rd interval, neither A nor B can be done, so you idle. By the 4th interval, you can do A again as 2 intervals have passed.
**Example 2:**
**Input:** tasks = ["A","C","A","B","D","B"], n = 1
**Output:** 6
**Explanation:** A possible sequence is: A -> B -> C -> D -> A -> B.
With a cooling interval of 1, you can repeat a task after just one other task.
**Example 3:**
**Input:** tasks = ["A","A","A", "B","B","B"], n = 3
**Output:** 10
**Explanation:** A possible sequence is: A -> B -> idle -> idle -> A -> B -> idle -> idle -> A -> B.
There are only two types of tasks, A and B, which need to be separated by 3 intervals. This leads to idling twice between repetitions of these tasks.
**Constraints:**
- `1 <= tasks.length <= 104`
- `tasks[i]` is an uppercase English letter.
- `0 <= n <= 100`