CTU Open Contest 2019

Problem A

Solved by Kilo_5723. 00:36 (+5)

题意：求在所有由 $A$ 和 $B$ 组成的 $K$ 位数中，$C$ 出现的次数。

题解：如果 $C\neq A$ 且 $C \neq B$，则不会出现。

否则如果 $A=B$，则出现 $K$ 次。

否则，出现 $K \ctimes 2^{K-1}$ 次。

Problem B

Solved by Xiejiadong. 02:34(+)

按照题目意思计算即可。

题目却是比较难理解，看着样例大概猜了猜。

Problem C

Solved by Kilo_5723. 03:04 (+3)

Problem D

Solved by Xiejiadong. 04:08 (+)

Problem E

Solved by Weaver_zhu. 03:37 (+1)

Problem F

Solved by Kilo_5723. 02:05 (+1)

Problem G

Solved by Kilo_5723. 01:33 (+2)

Problem H

Solved by Xiejiadong. 02:53 (+2)

相对比较大的模拟题。时间顺序比较难处理（主要是题目没讲清楚）。

Problem I

Solved by Weaver_zhu. 4:07 (+3)

Problem J

Solved by Weaver_zhu. 02:20 (+)