Hiho! is a serial contests we developed to help programmers improve their skills following some architecture. After the problems in "String" serial, we now focus on "Dynamic programming". One of the core idea of Dynamic programming is not to calculate what has been calculated, not to calculate what is no used, and Hi call this idea "Release Redundancy". But this kind of technique is learning required. So we collect some classic dynamic programming problem here, analysis the redundancy in it, summerize the its regularity. Hope it will help your programming thinking.

And this week, Hi and Ho will introduce to you a method to solve length changable arrays in the state when solve dynamic programming problem - state compression. By combine the arrays into one number, we can easily avoid complex judgement. Also, for those who use binary conversion, bitwise calculation is a amazing way to optimize your code. So don't wait and learn it with Hi and Ho!