2019年4月12日
K - Wand（组合数+错排公式）
摘要： N wizards are attending a meeting. Everyone has his own magic wand. N magic wands was put in a line, numbered from 1 to n(Wand_i owned by wizard_i). A 阅读全文
posted @ 2019-04-12 23:33 cherish__lin 阅读(213) 评论(0) 推荐(0)