Subway Check-In Rules | Dataford Interview Questions

The Oscar Health member app records visit times for each member. Given a member's visit history and a proposed check-in time, determine whether the member can check in. A check-in is allowed only when the member has no earlier visit or at least 15 minutes have elapsed since their most recent visit.

Formal Specification

Implement can_check_in(visit_times, user_id, check_in_time), where visit_times is a dictionary mapping user IDs to sorted lists of integer timestamps, measured in minutes. Return a Boolean. Consider only visits at or before check_in_time; future visits must not affect the result. A member may check in exactly 15 minutes after the previous visit.

Constraints

0 <= len(visit_times[user_id]) <= 10^5
Each user's timestamps are sorted in nondecreasing order
0 <= timestamps and check_in_time <= 10^9
user_id may be absent from visit_times
The cooldown is exactly 15 minutes

Function Signature

def can_check_in(visit_times, user_id, check_in_time):

Your question is Subway Check-In Rules. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Formal Specification

Constraints

0 <= len(visit_times[user_id]) <= 10^5
Each user's timestamps are sorted in nondecreasing order
0 <= timestamps and check_in_time <= 10^9
user_id may be absent from visit_times
The cooldown is exactly 15 minutes

Function Signature

def can_check_in(visit_times, user_id, check_in_time):

Your question is Subway Check-In Rules. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.