丟進 array 是 OK 的,但問題在於他需要判斷 entry 是否重複,卻沒有用 hash 或是 tree 的結構,而這邊大約有 63k 筆資料,用 array 實做就產生了 O(n^2) 的演算法:
But before it’s stored? It checks the entire array, one by one, comparing the hash of the item to see if it’s in the list or not. With ~63k entries that’s (n^2+n)/2 = (63000^2+63000)/2 = 1984531500 checks if my math is right. Most of them useless. You have unique hashes why not use a hash map.
if it’s called again within the string’s range, return cached value
而第二個問題他直接把檢查是否有重複的跳過,因為資料本身不重複:
And as for the hash-array problem, it’s more straightforward - just skip the duplicate checks entirely and insert the items directly since we know the values are unique.
I found this while making a collection of what C implementation does what at https://news.ycombinator.com/item?id=26298300.
There are two basic implementation strategies. The BSD (FreeBSD and OpenBSD and more than likely NetBSD too), Microsoft, GNU, and MUSL C libraries use one, and suffer from this; whereas the OpenWatcom, P.J. Plauger, Tru64 Unix, and my standard C libraries use another, and do not.
The 2002 report in the comp.lang.c Usenet newsgroup (listed in that discussion) is the earliest that I've found so far.
Starting in October 2016, you will be able to store all your critical C14 data in our fallout shelter, located 26 meters underground in Paris, France.
整個計畫在 2012 年從法國政府買下來,然後開始重建:
In 2011, the French state, owner of the building, decided to move the Ponts et Chaussées' central laboratory in the Parisian suburb and started to dismantle the building.
The Ponts et Chaussées' central laboratory buildings were revamped and divided in multiple bundles to be sold and transformed in multi-unit housing. The main building and the shelter were sold separately via a public invitation to tender. Online landed the deal in September 2012 with the project to build a Datacenter. The project’s codename is DC4.