How should I practice Earliest One-Hour Badge Alert Times?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Robinhood phone screen problems in FastPrep.

Is Earliest One-Hour Badge Alert Times associated with Robinhood?

FastPrep tags this as a Robinhood phone screen coding practice problem when the problem catalog has that company and stage context.

Earliest One-Hour Badge Alert Times

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Problem statement

The parallel arrays keyName and keyTime describe unordered badge events: entry i records employee keyName[i] badging in at keyTime[i]. Each time is a valid 24-hour string in HH:MM format. All events occur during a single day.

Find every employee with at least three badge events in an inclusive one-hour period. If several such periods exist, select the earliest one for that employee. Return every badge time in that selected hour, rather than only the first three.

For this exercise, assume each candidate hour starts at one of the employee's badge events and spans the next 60 minutes, including both endpoints. An hour does not wrap across midnight.

For this exercise, assume every time has exactly five characters and uses two digits for the hour and minute.

Return one row [employee,time1,time2,...] per qualifying employee. For this exercise, assume employee rows are sorted lexicographically; times are sorted chronologically while retaining their original text, and equal times preserve input order. Each record counts separately, even when the employee and time are repeated. An empty input returns an empty result.

Function

badgeAlerts(keyName: String[], keyTime: String[]) → String[][]

Examples

Example 1

keyName = ["daniel","daniel","daniel","daniel","daniel","daniel","luis","luis","luis","luis"]keyTime = ["10:00","10:40","10:50","10:51","10:55","11:00","09:00","11:00","13:00","15:00"]return = [["daniel","10:00","10:40","10:50","10:51","10:55","11:00"]]

The original report's earliest qualifying windows are retained, with employee rows sorted for this exercise. Every badge time within the selected hour is included.

Example 2

keyName = ["Amy","Amy","Amy","Amy","Bob","Bob","Bob"]keyTime = ["10:00","10:30","11:00","11:01","00:10","01:11","02:12"]return = [["Amy","10:00","10:30","11:00"]]

Amy's hour begins at 10:00 and includes the access exactly 60 minutes later. The next access is outside that hour; Bob has no qualifying hour.

Constraints

For this exercise, assume there are at most 2000 events.
Employee identifiers are nonempty case-sensitive alphanumeric strings of at most 30 characters.
Every time represents an hour from 0 through 23 and a minute from 0 through 59.
keyName.length == keyTime.length.