摘要: 题面 题解 容易发现答案就是 \(\displaystyle [x^{nd}] \left(\sum_{i \geq 0} [d|i] \frac {x^i}{i!}\right)^k\),对其进行单位根反演就是 \(\displaystyle [x^{nd}] \left(\frac 1d \su 阅读全文
posted @ 2021-03-12 11:27 xgzc 阅读(105) 评论(0) 推荐(0) 编辑