Max Traffic Time
Reported by candidates from IBM's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
IBM sent you a Max Traffic Time problem in August 2024, and you've got less than 72 hours to lock it down. This is a classic time-series or interval-based pattern that trips up candidates who overthink it. The problem usually boils down to finding a peak or aggregating traffic across overlapping windows. StealthCoder sits invisible on your machine during the live OA, ready to surface the pattern if you blank on approach. Most candidates solve this in 15-20 minutes once they see the trick.
Pattern and pitfall
Max Traffic Time typically asks you to find the timestamp or interval where traffic hits its highest point, often given as a list of events with start and end times, or as cumulative counts. The trap: candidates jump to sorting or a greedy scan without thinking about how to efficiently count overlaps. The pattern is usually a sweep-line algorithm (sort events, process in order, track active intervals) or a prefix-sum approach if traffic is bucketed by hour or minute. Edge cases kill here: ties, single events, or events that overlap at boundaries. During the live OA, if the logic isn't clicking, StealthCoder will remind you of the sweep-line structure so you don't waste 10 minutes on a brute-force nested loop.
Drill it cold or hedge it with StealthCoder. Either way, don't walk into the OA hoping you remember the trick.
You can drill Max Traffic Time cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Made for the candidate who got the OA invite this morning and has 72 hours, not six months.
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IBM reuses patterns across OAs. Made for the candidate who got the OA invite this morning and has 72 hours, not six months. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Max Traffic Time FAQ
Is this asking for the time itself, or the max traffic count?+
Usually the time or timestamp where traffic peaks. If multiple times tie, the problem statement will say which one to return (earliest, latest, or all). Read the output format in the prompt carefully. That's often where candidates miss points.
Do I need to sort the input?+
Almost always yes. Sorting events by start time (and breaking ties by type: arrivals before departures, or vice versa) is the foundation of the sweep-line approach. If you're not sorting, you're doing extra work.
What's the time complexity they expect?+
O(n log n) for sorting plus O(n) for the sweep is the standard. Brute force O(n^2) nested loops will time out on large inputs. Stay away from that trap.
How do I handle ties in traffic count?+
The problem statement will specify: return the earliest time, the latest, or all times tied for max. If it's silent, assume earliest. Always check the examples.
Can I solve this without sorting?+
Not efficiently. Sorting is non-negotiable here. If you're tempted to skip it, you're either misunderstanding the problem or about to write an O(n^2) solution. Neither is worth the risk.