摘要：
1006 Sign In and Sign Out （25 分） At the beginning of every day, the first person who signs in the computer room will unlock the door, and the last one 阅读全文
摘要：
1001 A+B Format （20 分） Calculate a+b and output the sum in standard format -- that is, the digits must be separated into groups of three by commas (un 阅读全文