DSA pattern
Intervals
Interval problems involve ranges with start and end points. The key insight is sorting (usually by start time) to enable efficient linear processing. Common operations include merging overlapping intervals and finding minimum resources.
When to use
5 signals- 01Merging overlapping intervals
- 02Finding free time slots
- 03Minimum meeting rooms
- 04Insert/delete intervals
- 05Non-overlapping interval selection
In interviews, call out the pattern early. It helps interviewers follow your reasoning and keeps your implementation focused. After solving, explain tradeoffs in plain language: why this approach is efficient, where it can break, and what edge cases you would test first.
Practice problems
5 listed- 01Merge IntervalsPractice →
- 02Insert IntervalPractice →
- 03Non-overlapping IntervalsPractice →
- 04Meeting RoomsPractice →
- 05Meeting Rooms IIPractice →
Build a review loop
Treat each pattern as a repeating cycle, not a one-time read. Solve a fresh problem today, revisit the same pattern in 2-3 days, and run one timed attempt at the end of the week. This turns short-term familiarity into reliable recall for live interviews.
When reviewing, re-derive the core steps from scratch before checking a reference solution. If you can explain the state transitions and edge cases clearly, you are much more likely to execute well under interview pressure.