摘要：
Description In the battlefield , an effective way to defeat enemies is to break their communication system. The information department told you that there are n... 阅读全文
摘要：
Description For the hope of a forever love, Steven is planning to send a ring to Jane with a romantic string engraved on. The string's length should not exceed N. The car... 阅读全文
摘要：
Description Biologists finally invent techniques of repairing DNA that contains segments causing kinds of inherited diseases. For the sake of simplicity, a DNA is represe... 阅读全文