Crossing Segments — Solution & Editorial

Back to the Problem

Segment intersection via orientation (signed cross product) tests plus the collinear-overlap special cases; check all pairs. (A Bentley–Ottmann sweep does O((N+K) log N).)

Complexity: O(N²)

Watch out: The collinear/endpoint-touching cases need the on-segment bounding-box check — pure sign tests miss them.