How should I practice Recursively Expanded Shell Command Counts?

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Recursively Expanded Shell Command Counts

ZipRecruiter● MediumNEW GRADOA

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Problem statement

Every history entry is cp, ls, mv, or !index, where index is one-based from the session start and refers to an earlier entry.

A reference recursively executes the referenced entry. Return counts in [cp, ls, mv] order, counting direct and referenced executions.

Function

countShellCommands(history: String[]) → int[]

Examples

Example 1

history = ["ls","cp","!1","!3","mv"]return = [1,3,1]

Entries 1, 3, and 4 all execute ls.

Example 2

history = ["cp","!1","!2"]return = [3,0,0]

Both references recursively resolve to cp.

Constraints

1 <= history.length <= 100000