摘要: 传送门 \(\sum_{i = 1}^{n}k \ mod \ i\) \(k \ mod \ i = k - \lfloor \frac{k}{i} \rfloor*i\) \(\sum_{i = 1}^{n}k \ mod \ i = kn - \sum_{i = 1}^{n}\lfloor \ 阅读全文
posted @ 2020-01-30 21:15 Emcikem 阅读(199) 评论(0) 推荐(0) 编辑