The algorithm maintains a running "best distance" that starts at infinity. As it walks the tree, it checks each visited point and updates the best distance if it finds something closer. Before recursing into a child node, it checks whether the closest possible point in that child's bounding box is farther than the current best. If so, the entire subtree gets pruned.
It is designed to fill the operational gap between simple chroot
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The performance impact on typical applications will be much smaller, since they don’t usually present walls of icons in their UI.
距离：孩子还小，离家近是核心指标，接送方便，也能让孩子多睡一会儿。所以方圆一公里范围成了主要选择点。