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You have devised a new encryption technique which encodes a message by inserting between its characters randomly generated strings in a clever way. Be 阅读全文
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DNA (Deoxyribonucleic Acid) is the molecule which contains the genetic instructions. It consists of four different nucleotides, namely Adenine, Thymine 阅读全文
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A character string is said to have period k if it can be formed by concatenating one or more repetitions of another string of length k. For example, t 阅读全文
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Trung is bored with his mathematics homeworks. He takes a piece of chalk and starts writing a sequence of consecutive integers starting with 1 to N (1 阅读全文
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An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. The molar mass of an organic compound is the 阅读全文
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There is an objective test result such as “OOXXOXXOOO”. An ‘O’ means a correct answer of a problem and an ‘X’ means a wrong answer. The score of each 阅读全文
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Contest time again! How excited it is to see balloons floating around. But to tell you a secret, the judges' favorite time is guessing the most popula 阅读全文
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Little Valentine liked playing with binary trees very much. Her favorite game was constructing randomly looking binary trees with capital letters in t 阅读全文