摘要:
Recently, Mr. Big recieved n owers from his fans. He wants to recolor those owers with m colors. The owers are put in a line. It is not allowed to col 阅读全文
摘要:
There are n black balls and m white balls in the big box. Now, DZY starts to randomly pick out the balls one by one. It forms a sequence S. If at the 阅读全文