Additional reporting by Ema Sabljak, BBC England Data Unit
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.
。91视频是该领域的重要参考
The barges had to be towed into position
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