2018 Multi-University, HDU Day 3

Problem A

Solved by kblack. 01:45 (+5)

Problem C

Solved by ultmaster. 00:53 (+)

题意：若干加边删边操作，每次操作后，询问图中 $1,2,\ldots,n/2$ 匹配的数目。

题解：由于 $n$ 很小，维护每一个子图 ($2^n$) 的匹配数目。加边的时候，把含有那条边的子图都加上去掉那条边的子图的部分的现有的值。删边同理。

ultmaster: 总觉得有什么地方不大对，但出乎意料地输出了正确的答案。（运气真好）

Problem D

Solved by ultmaster. 00:17 (+)

题意：求第 $k$ 个欧拉函数是合数的数。

题解：经典的打表找规律签到。

Problem F

Solved by zerol. 00:26 (+)

Problem G

Solved by ultmaster. 02:27 (+)

Problem I

Solved by kblack. 03:24 (+4)

Problem J

Unsolved. (-2)

Problem L

Solved by kblack. 00:22 (+)

Problem M

Solved by zerol. 03:40 (+)