Leetcode 3027. Find the Number of Ways to Place People II

Count ordered pairs of given points (Alice at the upper-left corner and Bob at the lower-right) such that the axis-aligned rectangle with those corners (possibly degenerate) contains no other points on its boundary or interior. The core challenge is counting empty axis-aligned rectangles under the dominance constraint x_A ≤ x_B and y_A ≥ y_B, a 2D range-counting / sweep-line pattern for efficiency.