riemann_的博客

一、Problem’ One unknown hacker wants to get the admin’s password of AtForces testing system, to get problems from the next contest. To achieve that, he sneaked into the administrator’s office and stole...

一、Problem On the well-known testing system MathForces, a draw of n rating units is arranged. The rating will be distributed according to the following algorithm: if k participants take part in this ev...

一、Problem A PIN code is a string that consists of exactly 4 digits. Examples of possible PIN codes: 7013, 0000 and 0990. Please note that the PIN code can begin with any digit, even with 0. Polycarp h...

一、Problem You have three piles of candies: red, green and blue candies: the first pile contains only red candies and there are r candies in it, the second pile contains only green candies and there a...