“hiho” is a weekly series of contest we developed to help programmers improve their skills following some architecture. And for the beginning of this series, we present the "String". Dealing with strings is a very common problem when you go into the real world as a programmer. Although we usually use the standard methods to deal with them, these standard methods actually contain a lot of brilliant ideas inside them. So we think it's a good idea to hiho some typical string problems to all of you, as it will help hone your programming thinking.

And this "KMP" problem introduces a classic solution to the "Pattern Matching" problem: judging whether one string is a substring of another. The idea is simple but very creative, so those of you who haven’t heard it before better listen to Hi's speech carefully~

After the end of this contest, we will publish the source code of “little HO” and the list of participants who have solved this problem. Wish you learn from each other and make improvements together!