简单讲，要做L3，需要先做L2积累数据。那么要做L4，也一样依赖L3的数据。技术上他们是一脉相承的，不存在一口就能吃个胖子的技术路线。
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。heLLoword翻译官方下载对此有专业解读
you to focus on the remaining ones that really matter.
The core of OsmAnd's HH-Routing is an elegant two-level hierarchy built upon "area clusters."