Hiho! is a serial contests we developed to help programmers improve their skills following some architecture. Tree, as a data struct, its most significant feature is that it can be divide in to several problem simply by its natural form, which it's similar to what we have told in "Dynamic Programming".

After two weeks of foreshadowing, this week we'll gonna talk about the offline algorithm of the "LCA" problem! An offline algorithm means you didn't response the request of users right after you received them. You usually wait for certain amount of requests or some time, then deal with all the requests togather. This will help reducing the time comlexity by shared the time to each request. And this method is worked perfectly in the "LCA" problem.