Task Scheduler

A CPU must run a list of tasks, each labelled with a capital letter; every task takes one time unit. Two runs of the same task must be at least n units apart — in between, the CPU runs other tasks or stays idle. What is the minimum total time to finish all tasks?

Input:

• line 1: L n — the number of tasks and the cooldown
• line 2: the L task letters (no spaces)

Output: the minimum number of time units.

Constraints: 1 ≤ L ≤ 10⁵, 0 ≤ n ≤ 100.

Example: AAABBB with n = 2 → A B idle A B idle A B → 8.

Think about it: the most frequent task decides the frame: (maxCount − 1) blocks of length n + 1, plus one slot for every task that reaches maxCount. If there are more tasks than that frame, there is no idling at all. A greedy simulation with a max-heap also works.