The quadtree is the two-dimensional case of a broader family of space-partitioning data structures. Octrees extend the same idea to three dimensions (splitting cubes into eight children), KD-trees use alternating axis-aligned splits (splitting along x, then y, then x again), and R-trees group nearby objects into bounding rectangles. Each variant makes different tradeoffs between construction time, query speed, and update cost.
"I have to walk two hours a day to come into town to get food," he says, preferring to find shelter outside of the city centre where he feels safer, sleeping in a one-man tent under a bridge.
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if (low = high) return; // 子数组长度<=1
第一百零八条 公安机关进行询问、辨认、勘验，实施行政强制措施等调查取证工作时，人民警察不得少于二人。