2018-2019 Southeastern European Regional Programming Contest (SEERC 2018)

Problem A

Unsolved. (-5)

题意：问有多少种方法将一个数拆成两个回文数。

题解：写了个暴力 T 飞。

Problem B

Solved by ultmaster. 01:32 (+)

题意：圆周上有 $n$ 个点均匀分布。求有多少三元点对满足能形成一个包含圆心的三角形。

题解：所有方案减去不好的就可以了。答案是 $\displaystyle \frac{n(n-1)(n-2)}{6} - n \sum_{i=0}^{(n-1)/2} i$。

处理 unsigned long long 要用到一点小技巧，把 2 和 3 先除掉。

Problem C

Solved by zerol. 00:53 (+)

Problem E

Solved by ultmaster. 00:36 (+)

Problem F

Solved by zerol & kblack. 03:29 (+2)

Problem G

Solved by kblack. 01:21 (+)

Problem I

Solved by kblack. 00:47 (+1)