在 Twitter 上看到 zmx 提了一個連結，講 Uber 年初時貼的「How We Built Uber Engineering’s Highest Query per Second Service Using Go」這篇文章的問題：
前 Bing 員工：買了 Bing 怎麼不問專家啊？Quadtree 降兩個數量級啊，不然你們自創的做了這個小修改也是降兩個數量級啊！https://t.co/nHw1DgmYtU
— Bill Zhong (@zmx) August 2, 2016
It is clear to me that the team at Uber under-engineered this problem. Thoughtfully designing this service could trim down the number of nodes by an order of magnitude and save hundreds of thousands of dollars each year. That may sound like pittance to a company valued at more than the GDP of Delaware, but in my eyes that’s the salaries of a few engineers and a few good engineers can go a long way. Maybe even further than the few extra Mercedes-Benz S-Classes they could add to their fleet from the money they could be saving...
先不提政治問題，上面提到的 Quadtree 算是簡單易懂的結構，好久沒看到這個資料結構了：