Interval Processing

Sort intervals by start point, then merge, insert, or count overlapping ranges in a single O(n) scan.

Sort intervals by start point, then merge, insert, or count overlapping ranges in a single O(n) scan.

After sorting by start time, any overlap can only occur between consecutive intervals — no interval can overlap one it has already fully passed.

Sorting by start time guarantees overlapping intervals are adjacent, reducing a pairwise O(n²) scan to a linear O(n) merge pass.

The merge condition (current.start ≤ prev.end) is O(1) per interval — each is examined once.