摘要：http://acm.hdu.edu.cn/showproblem.php?pid=4279Problem Description Here are two numbers A and B (0 < A <= B). If B cannot be divisible by A, and A and B are not co-prime numbers, we define A as a special number of B. For each x, f(x) equals to the amount of x’s special numbers. For example, f(6 阅读全文

摘要：http://acm.hdu.edu.cn/showproblem.php?pid=4287Problem Description We all use cell phone today. And we must be familiar with the intelligent English input method on the cell phone. To be specific, the number buttons may correspond to some English letters respectively, as shown below: 2 : a, b, c3 :.. 阅读全文

摘要：http://acm.hdu.edu.cn/showproblem.php?pid=2222Problem DescriptionIn the modern time, Search engine came into the life of everybody like Google, Baidu, etc.Wiskey also wants to bring this feature to his image retrieval system.Every image have a long description, when users type some keywords to find 阅读全文