Codeforces Global Round 8
F
Lamps on a Circle
Codeforces
2600
原题
← EG →
翻译中…

This is an interactive problem.

翻译中…

John and his imaginary friend play a game. There are $n$ lamps arranged in a circle. Lamps are numbered $1$ through $n$ in clockwise order, that is, lamps $i$ and $i + 1$ are adjacent for any $i = 1, \ldots, n - 1$, and also lamps $n$ and $1$ are adjacent. Initially all lamps are turned off.

翻译中…

John and his friend take turns, with John moving first. On his turn John can choose to terminate the game, or to make a move. To make a move, John can choose any positive number $k$ and turn any $k$ lamps of his choosing on. In response to this move, John's friend will choose $k$ consecutive lamps and turn all of them off (the lamps in the range that were off before this move stay off). Note that the value of $k$ is the same as John's number on his last move. For example, if $n = 5$ and John have just turned three lamps on, John's friend may choose to turn off lamps $1, 2, 3$, or $2, 3, 4$, or $3, 4, 5$, or $4, 5, 1$, or $5, 1, 2$.

翻译中…

After this, John may choose to terminate or move again, and so on. However, John can not make more than $10^4$ moves.

翻译中…

John wants to maximize the number of lamps turned on at the end of the game, while his friend wants to minimize this number. Your task is to provide a strategy for John to achieve optimal result. Your program will play interactively for John against the jury's interactor program playing for John's friend.

翻译中…

Suppose there are $n$ lamps in the game. Let $R(n)$ be the number of turned on lamps at the end of the game if both players act optimally. Your program has to terminate the game with at least $R(n)$ turned on lamps within $10^4$ moves. Refer to Interaction section below for interaction details.

翻译中…

For technical reasons hacks for this problem are disabled.

翻译中…

Interaction

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Initially your program will be fed a single integer $n$ ($1 \leq n \leq 1000$) — the number of lamps in the game. Then the interactor will wait for your actions.

翻译中…

To make a move, print a line starting with an integer $k$ ($1 \leq k \leq n$), followed by $k$ distinct integers $l_1, \ldots, l_k$ ($1 \leq l_i \leq n$) — indices of lamps you want to turn on. The indices may be printed in any order. It is allowed to try to turn on a lamp that is already on (although this will have no effect).

翻译中…

If your move was invalid for any reason, or if you have made more than $10^4$ moves, the interactor will reply with a line containing a single integer $-1$. Otherwise, the reply will be a line containing a single integer $x$ ($1 \leq x \leq n)$, meaning that the response was to turn off $k$ consecutive lamps starting from $x$ in clockwise order.

翻译中…

To terminate the game instead of making a move, print a line containing a single integer $0$. The test will be passed if at this point there are at least $R(n)$ lamps turned on (note that neither $R(n)$, nor the verdict received are not communicated to your program in any way). This action does not count towards the number of moves (that is, it is legal to terminate the game after exactly $10^4$ moves).

翻译中…

To receive the correct verdict, your program should terminate immediately after printing $0$, or after receiving $-1$ as a response.

翻译中…

Don't forget to flush your output after every action.

翻译中…

Note

翻译中…

When $n = 3$, any John's move can be reversed, thus $R(3) = 0$, and terminating the game immediately is correct.

翻译中…

$R(4) = 1$, and one strategy to achieve this result is shown in the second sample case.

翻译中…

Blank lines in sample interactions are for clarity and should not be printed.

翻译中…

样例

Input #1
3
Output #1
0
InputCopy OutputCopy
Input #2
4

1
Output #2
2 1 3

0
InputCopy OutputCopy
题目信息
题号
1368F
时间限制
2 s
内存限制
512 MB
标签
博弈论
模拟
交互题
数学

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。