I woke up in the morning and ate some bread and went to Yuyao Middle School with the army. After talking about the first question, I was deeply impressed. The general idea of the title is: There is a directed graph with n points and m edges, and there are p key points. Find a strongly connected subgraph containing the key points with the smallest number of points. The problem required here can be transformed into a subgraph containing all points with the smallest number of points, and all key points are reachable by two. We can first consider that when p is two points, we can use the dp method to find it. And when there are more than one p, the same idea can also be carried out, but it is done with sets, transfer closures and the like. It means that I don't really understand the piece of messing around with the collection. Then I talked about some miscellaneous topics, and I felt that I understood a part of it. There is also a question that is more deeply understood. The meaning of the question is: there is a grid of r*c, in which there are n points with values, and the value between two adjacent points does not exceed d, find the value of the points in the grid and the maximum value. 1<=r,c<=10^9. We can think of it like this, for two points, we make the intersection of their ranks and columns into a fake point value point, and then we can use some special properties of four points to form a rectangle to solve the problem.
At noon, I ate with Cptraser, Antiquality and CHJ bosses. However, I went to the campus of Yuyao Middle School for a while. I felt that it was a good campus. Of course, compared with qzez, I still think qzez is better. hhh.
I slept in the lecture hall again at noon, feeling refreshed and refreshed, and I immediately understood the lecture in the afternoon. The topic of TopCoder is about. The topic of round1 at the beginning is similar to the A and B questions on CF. They are all relatively watery questions, that is, a volume-calculating topic that was not completed due to poor mathematical skills. The topic of round2 that I talked about next started to be difficult. What are the two-difference questions, and the half-search question of Meet in middle, although algorithms like Meet in middle have only been taught by seniors, and I have never played it myself. , but after listening to it, I still feel that it is relatively simple, and I can try it more in the future. Then the round3, semifinal, and final questions are more difficult, and there are many algorithms that I don't know, such as 2-SAT, I still have to work harder to learn the algorithm!
Sitting next to Senior ZZK in the afternoon, I feel that he is really strong. He gave me ideas for many questions and introduced me to the 2-SAT algorithm. Want to learn from ZZK boss!
After having dinner at Yuyao Middle School in the evening (it must be said that the cafeteria of No. 2 Middle School is delicious), I went to test the machine. I felt very bored, so I went to the hotel after the test and wrote this travel note. (After all, it was requested by Brother Xiang, of course, it must be finished as soon as possible).