http://haiyangxu.github.io/posts/2014/2014-07-02-longest_substr_or_subsequence.html
http://www.cnblogs.com/en-heng/p/3963803.html
http://blog.csdn.net/hrn1216/article/details/51534607
http://haiyangxu.github.io/posts/2014/2014-07-02-longest_substr_or_subsequence.html
http://www.cnblogs.com/en-heng/p/3963803.html
http://blog.csdn.net/hrn1216/article/details/51534607