| AveragePermutation |
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| This is an interactive problem. |
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| There is a hidden permutation p of n, where n is even. You want to discover this permutation using queries. |
| Each query consists of asking about k specific positions a1, a2, ..., ak. The query is answered with 1 if the average of the elements at these positions is an integer, and 0 otherwise. |
| Note that permutations [p1, p2, ..., pn] and [n+1-p1, n+1-p2, ..., n+1-pn] are indistinguishable using these queries. Therefore, you are guaranteed that p1 ≤ n/2. |
| This problem is graded based on the number of queries you use. Specifically, your answer will be compared to a reference solution ref_queries. |
| Your final score will be calculated as the average of 100 * min((ref_queries + 1) / (your_queries + 1), 1) across all test cases. |
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| Input |
| The first line of the input contains an even integer n (2 ≤ n ≤ 800) indicating the length of the hidden permutation. |
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| Interaction |
| To ask a query, output one line. First output ? followed by a space, then print an integer k (1 ≤ k ≤ n), then print k distinct integers a1, a2, ..., ak (1 ≤ ai ≤ n) separated by spaces. After flushing your output, your program should read a single integer (0 or 1) indicating whether the average is an integer. |
| If you want to guess the permutation, output one line. First output ! followed by a space, then print a permutation of n separated by spaces, satisfying the constraint that p1 ≤ n/2. After flushing your output, your program should exit immediately. |
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| Note that the answer for each test case is pre-determined. That is, the interactor is not adaptive. Also note that your guess does not count as a query. |
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| To flush your output, you can use: |
| fflush(stdout) (if you use printf) or cout.flush() (if you use cout) in C and C++. |
| System.out.flush() in Java. |
| stdout.flush() in Python. |
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| Time limit: 4 seconds |
| Memory Limit: 256 MB |
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| Example input: |
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| ? 2 1 2 |
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| ! 1 3 2 |
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| Example output: |
| 3 |
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| 1 |
