How should I practice Minimum Days for Fixed-Order Tasks with Cooldown?

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Problem · Array

Minimum Days for Fixed-Order Tasks with Cooldown

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Problem statement

You are given an array tasks of string task IDs and a nonnegative integer cooldown. Execute every task exactly once, in the supplied order, with at most one task executed per day.

If the same task ID was last executed on day d, its next execution must be no earlier than day d + cooldown + 1. You may insert idle days, but you may not reorder tasks.

Return the minimum total number of days needed to execute the complete sequence. Return 0 when tasks is empty.

Function

minimumDays(tasks: String[], cooldown: int) → long

Examples

Example 1

tasks = ["A","B","A"]cooldown = 2return = 4

Execute A on day 1 and B on day 2. Day 3 must be idle, so the second A runs on day 4.

Example 2

tasks = ["x","x","x"]cooldown = 0return = 3

With a zero-day cooldown, equal tasks may run on consecutive days.

Example 3

tasks = []cooldown = 5return = 0

No execution days are needed for an empty sequence.

Constraints

0 <= tasks.length <= 100000.
Each task ID is a non-empty string containing at most 50 Unicode characters.
0 <= cooldown <= 1000000000.
Tasks must be executed in their given order.
The answer fits in a signed 64-bit integer.