LeetCode 56 ·
Medium
Merge Intervals
Merge all overlapping intervals.
Try it
Step through the core mechanic. The simulator below runs the greedy shape this problem is built on.
Walk the pattern
No dedicated step-through for this one yet. The shape is Greedy — its pattern page has the interactive walkthrough, the reference implementation, and a five-problem progression that this problem sits inside.
The approach
Sort by start. Walk the list, extending the current interval's end while the next start falls inside it; otherwise push the current and open a new one. Sorting is the whole trick.
| Aspect | Value |
|---|---|
| Pattern | Greedy |
| Recognise it by | Collapse overlapping intervals. |
| Time complexity | O(n log n) |
| Space complexity | O(n) |
| Difficulty | Medium |
Who asks it
Companies known to ask this problem, from public LeetCode company-tag aggregations. A signal of where to expect it, not a guarantee.