POI (Point of Interest)
A1. GeoHash
A2. K-D Tree
A3. Space-filling Curve
Spatial Indexing
Quadtree
Hilbert Curves
Yelp: find nearest restaurants/...etc baes on the location of user (Given longitude and latitude also a radius)
原文：https://www.cnblogs.com/wangby511/p/12468828.html