Google · L4 (5 years)

Rounds

1. Virtual interview

Questions asked

• Given on-call rotation schedules for multiple people, each with a unique name, start time, and end time, return a rotation table of non-overlapping time intervals showing who is on call during each interval. Exclude intervals where nobody is on call. Implement:

public static List<OncallOutput> getIntervals(List<OncallInput> input)

record OncallInput(String name, int start, int end) {}
record OncallOutput(int start, int end, List<String> names) {}

Example input:

• Abby: [1, 10)
• Ben: [5, 70)
• Carla: [6, 12)
• David: [15, 30)

Example output:

• [1,5) → Abby
• [5,6) → Abby, Ben
• [6,10) → Abby, Ben, Carla
• [10,12) → Ben, Carla
• [12,15) → Ben
• [15,30) → Ben, David
• [30,70) → Ben

Tips

• Think of it as a sweep line: collect all start/end points, sort them, and track who is active between each pair of points.