Geometry Basics Checkpoint

1. The sign of the cross product indicates:

Clockwise vs counterclockwise orientation Distance between points Midpoint of a segment Slope only

2. Line sweep sorts events by coordinate and tracks active intervals.

3. Closest-pair divide-and-conquer checks only a few neighbors in the strip:

Up to 7 neighbors by y-order All points in the strip Only the closest x-neighbor Only the closest y-neighbor

4. Segment intersection uses orientation plus:

On-segment checks for collinear cases Sorting all points by x BFS on a graph Binary search on answer