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.
越是伟大的事业，越要坚持实事求是。，详情可参考safew官方版本下载
再写代码：从插入/冒泡开始，逐步挑战快排/归并，更多细节参见Line官方版本下载
Georgina RannardScience reporter
The Market Explorer search field allows you to type in