KMP + Manacher
https://github.com/julycoding/The-Art-Of-Programming-ByJuly/blob/master/ebook/zh/01.01.md(字符串循环左移)
http://bbs.dlut.edu.cn/bbstcon.php?board=Competition&gid=23474(最长回文子串)
http://www.felix021.com/blog/read.php?2040 (最长回文子串)
http://leetcode.com/2011/11/longest-palindromic-substring-part-ii.html (最长回文子串)
http://baike.baidu.com/view/1436430.htm(字符串匹配)
http://www.cppblog.com/abilitytao/archive/2009/08/01/91865.html(KMP)
http://zh.wikipedia.org/wiki/DFA(DFA)
http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2177(周期串)
http://baike.baidu.com/view/1240197.htm(后缀数组)
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