System Design Article

Design Google Maps

Difficulty: Hard

Design Google Maps: a global mapping service that renders the Earth from 256x256 tiles, computes the shortest driving route in under 200 ms, and folds live traffic into routing for 1B users issuing 5B route requests per day. The interview centerpiece is the routing engine: how Dijkstra is too slow on a continent-scale graph and how Contraction Hierarchies (CH) precompute shortcuts so the live query is logarithmic. We cover the tile pyramid (zoom 0-20, ~1 trillion possible tiles at zoom 20), how live traffic from 100M Android phones updates edge weights every minute, and how to keep navigation latency under 1 second when re-routing.