參考:
史上最強算法論戰：請不要嘻哈，這是哈希
http://chuansong.me/n/1483028
minimal perfect hash function
https://en.wikipedia.org/wiki/Perfect_hash_function
Comparison of Hash Table Libraries
https://attractivechaos.wordpress.com/2008/08/28/comparison-of-hash-table-libraries/
史上最強算法論戰：請不要嘻哈，這是哈希
http://www.cnblogs.com/yymn/p/4604532.html
http://mp.weixin.qq.com/s?__biz=MjM5MTQzNzU2NA==&mid=207841440&idx=1&sn=e7c993bfdd5d39de9c24a6730f78ce5e&scene=1&from=singlemessage&isappinstalled=0#rd