ACM-ICPC 2018 Xuzhou Online Contest

ECNU Foreigners

Problem A

Solved by ultmaster. 01:19 (+)

Problem B

Solved by kblack. 01:16 (+1)

Problem C

Solved by ultmaster. 02:56 (+2)

Problem D

Solved by zerol. 00:59 (+2)

题意：求 $\sum_{i=1}^m \mu(in)$

题解：如果 $n$ 中有平方因子，那么显然答案是 0。否则相当于求 $\mu(n) \cdot \sum_{i=1}^m \mu'(i)$，其中 $\mu'$ 是在 $\mu$ 的基础上不把 $n$ 的质因数当质数。类似于求 $\mu$ 的前缀和的方法（任意一种亚线性筛），改一改就能过了。

Problem F

Solved by ultmaster. 00:26 (+)

Problem G

Solved by kblack. 00:34 (+)

Problem H

Solved by zerol. 01:16 (+)

Problem I

Solved by kblack. 00:16 (+)

Problem J

Solved by kblack. 02:42 (+3)

Problem K

Solved by zerol. 02:51 (+6)