摘要：
Sometimes some mathematical results are hard to believe. One of the common problems is the birthday paradox. Suppose you are in a party where there ar 阅读全文
摘要：
When Kefa came to the restaurant and sat at a table, the waiter immediately brought him the menu. There were n dishes. Kefa knows that he needs exactl 阅读全文
摘要：
Problem Description In the battlefield , an effective way to defeat enemies is to break their communication system.The information department told you 阅读全文
摘要：
The country Treeland consists of n cities, some pairs of them are connected with unidirectional roads. Overall there are n - 1 roads in the country. W 阅读全文
摘要：
You, the leader of Starship Troopers, are sent to destroy a base of the bugs. The base is built underground. It is actually a huge cavern, which consi 阅读全文
摘要：
In the new ACM-ICPC Regional Contest, a special monitoring and submitting system will be set up, and students will be able to compete at their own uni 阅读全文
摘要：
After Farmer John realized that Bessie had installed a "tree-shaped" network among his N (1 <= N <= 10,000) barns at an incredible cost, he sued Bessi 阅读全文
摘要：
Last years Chicago was full of gangster fights and strange murders. The chief of the police got really tired of all these crimes, and decided to arres 阅读全文
摘要：
There is going to be a party to celebrate the 80-th Anniversary of the Ural State University. The University has a hierarchical structure of employees 阅读全文
摘要：
A school bought the first computer some time ago(so this computer's id is 1). During the recent years the school bought N-1 new computers. Each new co 阅读全文