2018 Multi-University, HDU Day 10

A. Alkane

solved by Baidu & OEIS. 3:18(+)

E. TeaTree

solved by CSL. 3:01(+1)

G. Cyclic

solved by CSL. 0:22(+)

H. Pow

solved by Moira. 0:11(+1)

I. Count

solved by CSL. 1:29.(+)

Comment:

  • ,先枚举再枚举
  • 即对于每个,求有多少个小于它的满足是奇数。
  • 是奇数时,答案为
  • 是偶数时,答案为
  • 线性筛加前缀和预处理即可。

J. CSGO

solved by Moira. 2:42(+)

K. Pow2

solved by CSL. 4:44(+)

L. Videos

solved by CSL. 1:08(+2)