摘要：
A crossword puzzle consists of a rectangular grid of black and white squares and two lists of definitions (or descriptions).One list of definitions is... 阅读全文
摘要：
A children's puzzle that was popular 30 years ago consisted of a 5x5 frame which contained 24 small squares of equal size. A unique letter of the alph... 阅读全文
摘要：
A character string is said to have periodkif it can be formed by concatenating one or more repetitions of another string of lengthk. For example, the ... 阅读全文
摘要：
Trung is bored with his mathematics homeworks. He takes a piece of chalk and starts writing a sequence of consecutive integers starting with 1 toN(1 #... 阅读全文