A quadtree does the same thing for two-dimensional space. It takes a rectangular region and divides it into four equal quadrants: northwest, northeast, southwest, southeast. If a quadrant has too many points in it, it subdivides again and again. Each subdivision creates smaller and smaller cells where points are densely packed.
item = parse_detail(u, d)。关于这个话题，爱思助手下载最新版本提供了深入分析
，这一点在Line官方版本下载中也有详细论述
Что думаешь? Оцени!，详情可参考safew官方版本下载
The tree behind the grid