codeforces#P1621C. Hidden Permutations
Hidden Permutations
Description
This is an interactive problem.
The jury has a permutation $p$ of length $n$ and wants you to guess it. For this, the jury created another permutation $q$ of length $n$. Initially, $q$ is an identity permutation ($q_i = i$ for all $i$).
You can ask queries to get $q_i$ for any $i$ you want. After each query, the jury will change $q$ in the following way:
- At first, the jury will create a new permutation $q'$ of length $n$ such that $q'_i = q_{p_i}$ for all $i$.
- Then the jury will replace permutation $q$ with pemutation $q'$.
You can make no more than $2n$ queries in order to quess $p$.
The first line of input contains a single integer $t$ ($1 \leq t \leq 1000$) — the number of test cases.
Interaction
Interaction in each test case starts after reading the single integer $n$ ($1 \leq n \leq 10^4$) — the length of permutations $p$ and $q$.
To get the value of $q_i$, output the query in the format $?$ $i$ ($1 \leq i \leq n$). After that you will receive the value of $q_i$.
You can make at most $2n$ queries. After the incorrect query you will receive $0$ and you should exit immediately to get Wrong answer verdict.
When you will be ready to determine $p$, output $p$ in format $!$ $p_1$ $p_2$ $\ldots$ $p_n$. After this you should go to the next test case or exit if it was the last test case. Printing the permutation is not counted as one of $2n$ queries.
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.
It is guaranteed that the sum of $n$ over all test cases doesn't exceed $10^4$. The interactor is not adaptive in this problem.
Hacks:
To hack, use the following format:
The first line contains the single integer $t$ — the number of test cases.
The first line of each test case contains the single integer $n$ — the length of the permutations $p$ and $q$. The second line of each test case contains $n$ integers $p_1, p_2, \ldots, p_n$ — the hidden permutation for this test case.
Input
The first line of input contains a single integer $t$ ($1 \leq t \leq 1000$) — the number of test cases.
Samples
2
4
3
2
1
4
2
4
4
? 3
? 2
? 4
! 4 2 1 3
? 2
? 3
? 2
! 1 3 4 2
Note
In the first test case the hidden permutation $p = [4, 2, 1, 3]$.
Before the first query $q = [1, 2, 3, 4]$ so answer for the query will be $q_3 = 3$.
Before the second query $q = [4, 2, 1, 3]$ so answer for the query will be $q_2 = 2$.
Before the third query $q = [3, 2, 4, 1]$ so answer for the query will be $q_4 = 1$.
In the second test case the hidden permutation $p = [1, 3, 4, 2]$.
Empty strings are given only for better readability. There will be no empty lines in the testing system.