Algorithm - 2023.2 English

There are n nodes (rectangles), and the center point of its i-th node is represented as (xi, yi). A parent node has at most r child nodes.

1. Sort all nodes according to x.

2. Divide all nodes into sqrt (n/r) parts, each of which is sorted by y.

3. Every r nodes are merged into a new parent node.
4. Repeat (1)~(3) until the number of parent nodes is 1.