The 36th ACM/ICPC Asia Regional Chengdu site -- online contest QUESTION Report

2011 ACM/ICPC Chengdu regional preliminary question report
Source: Oracle macro logs
Sorry!

I am very sorry for the large accident!

Then, let's write down the question report briefly. Before the question is given, we set the principle to go through the no-test template questions, take more test on some thinking questions, and finally basically achieve this. In addition, if you do not reveal the question, try to give the example a little better, so that the pressure on OJ is lower. In fact, after the question is added, I feel that the time limit for some questions is too long, it puts more pressure on the server, so the data is reduced.

1001: Line Segment tree. The mark is an offline algorithm. The line segment tree is created by time and inserted in the order of intervals. The complexity is O (qtlogn). It is visually tested, several of them are online algorithms, indicating they are not understood. The experts who have obtained questions will release another solution. In addition, the three-second time limit for this question was handed over nearly 500 TLE, indicating that hdoj is still very powerful.

1002: in fact, as long as the various rules are correctly written, the standard process is 486 ms, and the 5-Second time limit should be very generous. Unfortunately, no one wrote the whole site, the submitted code is basically output by Rand. We have more than 6000 sets of data, and enumerate the combinations of all the card picking rules to ensure that the code can be written correctly. This requires rand to pass, it is estimated that the RP will be exhausted for a lifetime.

1003: This question was temporarily replaced last night. The reason is that the original 1003 questions are the same as the 1010 questions in the FDU online competition yesterday, but the background of our questions is to cut fruit. Such a hit question event is really speechless, so last night, we asked the great god of HL to withdraw the report on understanding the question, and told me a little bit about the question. Now we know why... Thank you for your help! The solution to this question is actually the length of the two sides, and then the cosine theorem calculates the inner angle and whether it is 360. A trick is to note that the side length must satisfy the interest of forming a triangle.

1004: Enumerate one of the shortest paths and see if it can be added by the other two shortest paths.

1005: tree-like DP, the probability of pushing is a little annoying, but the sample is very strong, and SPJ gives a wide range of precision, basically pass through the sample. In addition, similar questions can be iterated in the past. This question specifically produces data, and the goal is to break down these messy algorithms.

1006: I am sorry for the error in the example. Fortunately, the problem was found early, which did not have a great impact on the competition. The algorithm for this question is very simple. It can be determined by the mountain valley points and bad sweet potatoes. The basic conservation of energy is enough. The weight of each sweet potato is to confuse everyone, the result is the most frequently asked questions on Clar ......

1007: English writing is poor. It was a simple question. As a result, we found that it was too late, resulting in too few people ...... In fact, each time point corresponds to an equal difference series. I want to write a question surface to hide this, and the result is hidden too deep ...... Separate C and D to create a line segment tree. In fact, this is a simple question. Ah ...... This question is too regrettable. It was originally positioned as the most simple mid-range question, and the result was directly promoted to a difficult problem.

1008, so I changed the modulo of a large prime number and forgot to modify the result. I'm sorry! One conclusion of this question is: if the current minimum number is greater than or equal to 3, and m is greater than or equal to 3, the optimal method is to open a new number. The rest is the discussion.

1009: The sample is cool. Are HH and L + Q not angry ?! The solution is simple, that is, direct BFS Layer 2. It is slow to enumerate one person and calculate the number of mutual friends.

In the end, it was really difficult to give a question. For a week in a row, I slept at three o'clock every night. I thought it was a success. Yesterday I encountered a question hit, another night ...... However, none of these can be the cause of 1008 errors. I'm sorry! Sorry again!

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