ICL 2016 (GP of Tatarstan)

Problem A

Upsolved by ultmaster. (-2)

题意：给定三点 $A,B,C$，求一点 $Q$ 使得 $AQB = \alpha_1$, $BQC = \alpha_2$。

题解：搞出四个圆，然后两两配对。注意交点不能和给定点重合，注意圆重合的情况。

Problem B

Unsolved. (-10)

Problem C

Solved by ultmaster. 01:34 (+1)

题意：有 $n$ 个东西，每个东西已知一些事件发生，求在此条件下 另一系列事件发生的概率。

题解：条件概率公式。注意权重。

Problem D

Unsolved.

Problem E

Unsolved.

Problem F

Solved by ultmaster. 00:42 (+1)

题意：问有多少个有序数列满足 gcd 是 d，lcm 是 m。

题解：m /= d。然后简单容斥一下。

Problem G

Solved by zerol. 00:13 (+)

Problem H

Solved by zerol. 01:36 (+2)

Problem I

Solved by zerol. 00:49 (+)

Problem J

Solved by zerol. 03:21 (+2)

Problem K

Solved by kblack. 02:06 (+1)

Problem L

Solved by kblack. 02:56 (+3)

Problem M

Solved by kblack. 00:07 (+)