[PKU] P3062: Celebrity jeopardy
Description It’s hard to construct a problem that’s so easy that everyone will get it, yet still difficult enough to be worthy of some respect. Usually, we err on one side or the other....
Computer Security, Life, and others
Description It’s hard to construct a problem that’s so easy that everyone will get it, yet still difficult enough to be worthy of some respect. Usually, we err on one side or the other....
Description Julius Caesar lived in a time of danger and intrigue. The hardest situation Caesar ever faced was keeping himself alive. In order for him to survive, he decided to create one of the...
Description In 1949 the Indian mathematician D.R. Kaprekar discovered a class of numbers called self-numbers. For any positive integer n, define d(n) to be n plus the sum of the digits of n. (The...
Description Computing the exact number of ways that N things can be taken M at a time can be a great challenge when N and/or M become very large. Challenges are the stuff of...
Description Larry graduated this year and finally has a job. He’s making a lot of money, but somehow never seems to have enough. Larry has decided that he needs to grab hold of his...
Description How far can you make a stack of cards overhang a table? If you have one card, you can create a maximum overhang of half a card length. (We’re assuming that the cards...
Description Businesses like to have memorable telephone numbers. One way to make a telephone number memorable is to have it spell a memorable word or phrase. For example, you can call the University of...