KMP算法介绍
http://www.ruanyifeng.com/blog/2013/05/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm.html
为什么java的String没有用KMP
http://www.zhihu.com/question/27852656
http://stackoverflow.com/questions/19543547/why-jdks-string-indexof-does-not-use-kmp
原文：http://www.cnblogs.com/zhangali/p/4642415.html