codeforces#P1407C. Chocolate Bunny
Chocolate Bunny
Description
This is an interactive problem.
We hid from you a permutation $p$ of length $n$, consisting of the elements from $1$ to $n$. You want to guess it. To do that, you can give us 2 different indices $i$ and $j$, and we will reply with $p_{i} \bmod p_{j}$ (remainder of division $p_{i}$ by $p_{j}$).
We have enough patience to answer at most $2 \cdot n$ queries, so you should fit in this constraint. Can you do it?
As a reminder, a permutation of length $n$ is an array consisting of $n$ distinct integers from $1$ to $n$ in arbitrary order. For example, $[2,3,1,5,4]$ is a permutation, but $[1,2,2]$ is not a permutation ($2$ appears twice in the array) and $[1,3,4]$ is also not a permutation ($n=3$ but there is $4$ in the array).
The only line of the input contains a single integer $n$ ($1 \le n \le 10^4$) — length of the permutation.
Interaction
The interaction starts with reading $n$.
Then you are allowed to make at most $2 \cdot n$ queries in the following way:
- "? x y" ($1 \le x, y \le n, x \ne y$).
After each one, you should read an integer $k$, that equals $p_x \bmod p_y$.
When you have guessed the permutation, print a single line "! " (without quotes), followed by array $p$ and quit.
After printing a query do not forget to output end of line and flush the output. Otherwise, you will get Idleness limit exceeded. To do this, use:
- fflush(stdout) or cout.flush() in C++;
- System.out.flush() in Java;
- flush(output) in Pascal;
- stdout.flush() in Python;
- see documentation for other languages.
Exit immediately after receiving "-1" and you will see Wrong answer verdict. Otherwise you can get an arbitrary verdict because your solution will continue to read from a closed stream.
Hack format
In the first line output $n$ ($1 \le n \le 10^4$). In the second line print the permutation of $n$ integers $p_1, p_2, \ldots, p_n$.
Input
The only line of the input contains a single integer $n$ ($1 \le n \le 10^4$) — length of the permutation.
Samples
3
1
2
1
0
? 1 2
? 3 2
? 1 3
? 2 1
! 1 3 2