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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.
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Bigger, better, bolder is the message being touted about the first of this year's London fashion weeks.
内存成本暴涨 300%，中国手机市场进入「大涨价元年」，千元机加速消失
In 2011, hackers successfully cracked the main Linux development site, kernel.org. Afterward, to make sure this didn't happen again, the kernel's PGP web of trust was explicitly "bootstrapped" at a face-to-face key‑signing session during the 2011 Kernel Summit.