North American Invitational Programming Contest 2018 (NAIPC 2018)

Problem A

Unsolved.

Problem B

Unsolved.

Problem C

Upsolved by Xiejiadong.(-5)

题意：给出$n$盏灯的初始状态，每次按开关，从按的位置开始，每一时刻都会有后面一个灯转换状态，求变成目标状态最小需要的次数。

题解：$n\le 16$考虑状态压缩。

其实，抽象一下这道题目，可以看作是好多段长度不同的$1$异或起来，以达到目标状态。

用$f[i][j]$表示已经按了$i$次，状态为$j$时候存在，直接暴力枚举转移即可。时间复杂度$O(2^n\times n^2)$

没有看到状态处理的时候溢出了，怎么都过不了。

Problem D

Solved by Xiejiadong. 00:11:06(+)

非常温暖的签到题。

Problem E

Solved by Xiejiadong. 02:44:14(+4)

Problem F

Unsolved.

Problem G

Unsolved.

Problem H

Solved by Xiejiadong. 02:23:59(+)

Problem I

Unsolved.

Problem J

Unsolved.

Problem K

Solved by Xiejiadong. 04:58:11(+3)