ACM 1083.

Moving tables
Time Limit: 1000 ms memory limit: 10000 K
Total submit: 2352 accepted: 880

Description
The famous ACM (advanced computer maker) company has rented a floor of a building whose shape is in the following figure.

The floor has 200 rooms each on the North Side and south side along the corridor. recently the company made a plan to reform its system. the reform provided des moving a lot of tables between rooms. because the corridor is narrow and all the tables are big, only one table can pass through the corridor. some plan is needed to make the moving efficient. the manager figured out the following plan: moving a table from a room to another room can be done within 10 minutes. when moving a table from room I to room J, the part of the corridor between the front of room I and the front of room J is used. so, during each 10 minutes, several moving between two rooms not sharing the same part of the corridor will be done simultaneously. to make it clear the manager has strated the possible cases and impossible cases of simultaneous moving.

For each room, at most one table will be either moved in or moved out. now, the manager seeks out a method to minimize the time to move all the tables. your job is to write a program to solve the manager's problem.

 

Input
The input consists of T test cases. the number of test cases) (T is given in the first line of the input file. each test case begins with a line containing an integer N, 1 <= n <= 200, that represents the number of tables to move.
Each of the following n lines contains two positive integers S and T, representing that a table is to move from room number S to room number t each room number appears at most once in the n lines ). from the 3 + N-Rd
Line, the remaining test cases are listed in the same manner as abve.

Output
The output shoshould contain the minimum time in minutes to complete the moving, one per line.

Sample Input

3410 2030 4050 6070 8021 32 200310 10020 8030 50
 

 

Sample output

 
102030
 

Today, I wrote 1083 questions on PKU. it's hard to know how to use dynamic planning .. I do not know how to find the optimal sub-structure. I tried it several times with a hard head, and there was no progress. I had to turn to discuss for help. one idea is really too Second: first number each corridor from 1 to 200. after the number, each time a table is moved, the number of times the corridor section used during the movement is recorded plus one. finally, the maximum number of times used in all corridor sections is multiplied by 10, which is the minimum moving time.
This idea is amazing, too. this is also true in real life. therefore, you must learn and use it. dynamic Planning is difficult, but as long as we have more brains and more practical information. some clever ideas are often formed.