Codeforces Round 882 (Div. 2)
E
Triangle Platinum?
Codeforces
2900
原题
← DF →
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This is an interactive problem.

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Made in Heaven is a rather curious Stand. Of course, it is (arguably) the strongest Stand in existence, but it is also an ardent puzzle enjoyer. For example, it gave Qtaro the following problem recently:

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Made in Heaven has $n$ hidden integers $a_1, a_2, \dots, a_n$ ($3 \le n \le 5000$, $1 \le a_i \le 4$). Qtaro must determine all the $a_i$ by asking Made in Heaven some queries of the following form:

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  • In one query Qtaro is allowed to give Made in Heaven three distinct indexes $i$, $j$ and $k$ ($1 \leq i, j, k \leq n$).
  • If $a_i, a_j, a_k$ form the sides of a non-degenerate triangle$^\dagger$, Made in Heaven will respond with the area of this triangle.
  • Otherwise, Made in Heaven will respond with $0$.
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By asking at most $5500$ such questions, Qtaro must either tell Made in Heaven all the values of the $a_i$, or report that it is not possible to uniquely determine them.

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Unfortunately due to the universe reboot, Qtaro is not as smart as Jotaro. Please help Qtaro solve Made In Heaven's problem.

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——————————————————————

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$^\dagger$ Three positive integers $a, b, c$ are said to form the sides of a non-degenerate triangle if and only if all of the following three inequalities hold:

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  • $a+b \gt c$,
  • $b+c \gt a$,
  • $c+a \gt b$.
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Interaction

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The interaction begins with reading $n$ ($3 \le n \le 5000$), the number of hidden integers.

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To ask a question corresponding to the triple $(i, j, k)$ ($1 \leq i \lt j \lt k \leq n$), output "? $i$ $j$ $k$" without quotes. Afterward, you should read a single integer $s$.

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  • If $s = 0$, then $a_i$, $a_j$, and $a_k$ are not the sides of a non-degenerate triangle.
  • Otherwise, $s = 16 \Delta^2$, where $\Delta$ is the area of the triangle. The area is provided in this format for your convenience so that you need only take integer input.
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If the numbers $a_i$ cannot be uniquely determined print "! $-1$" without quotes. On the other hand, if you have determined all the values of $a_i$ print "! $a_1$ $a_2$ $\dots$ $a_n$" on a single line.

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The interactor is non-adaptive. The hidden array $a_1, a_2, \dots, a_n$ is fixed beforehand and is not changed during the interaction process.

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After printing a query do not forget to output the end of line and flush the output. Otherwise, you will get Idleness limit exceeded. To do this, use:

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  • fflush(stdout) or cout.flush() in C++;
  • System.out.flush() in Java;
  • flush(output) in Pascal;
  • stdout.flush() in Python;
  • see the documentation for other languages.
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Hacks

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You can hack a solution with the following input format.

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The first line contains a single integer $n$ ($3 \le n \le 5000$) — the number of hidden integers.

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The second line contains $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \le a_i \le 4$) — the hidden array.

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Note

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In the first example, the interaction process happens as follows:

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StdinStdoutExplanation3Read $n = 3$. There are $3$ hidden integers? 1 2 3Ask for the area formed by $a_1$, $a_2$ and $a_3$63Received $16\Delta^2 = 63$. So the area $\Delta = \sqrt{\frac{63}{16}} \approx 1.984313$! -1Answer that there is no unique array satisfying the queries.

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From the area received, we can deduce that the numbers that forms the triangle are either ($4$, $4$, $1$) or ($3$, $2$, $2$) (in some order). As there are multiple arrays of numbers that satisfy the queries, a unique answer cannot be found.

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In the second example, the interaction process happens as follows:

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StepStdinStdout****Explanation16Read $n = 6$. There are $6$ hidden integers2? 1 2 3Ask for the area formed by $a_1$, $a_2$ and $a_3$30Does not form a non-degenerate triangle4? 2 3 4Ask for the area formed by $a_2$, $a_3$ and $a_4$50Does not form a non-degenerate triangle6? 4 5 6Ask for the area formed by $a_4$, $a_5$ and $a_6$70Does not form a non-degenerate triangle8? 1 5 6Ask for the area formed by $a_1$, $a_5$ and $a_6$963Received $16\Delta^2 = 63$. So the area $\Delta = \sqrt{\frac{63}{16}} \approx 1.984313$10? 3 5 6Ask for the area formed by $a_3$, $a_5$ and $a_6$1115Received $16\Delta^2 = 15$. So the area $\Delta = \sqrt{\frac{15}{16}} \approx 0.968245$12? 1 2 4Ask for the area formed by $a_3$, $a_5$ and $a_6$13135Received $16\Delta^2 = 135$. So the area $\Delta = \sqrt{\frac{135}{16}} \approx 2.904738$14! 3 2 1 4 2 2A unique answer is found, which is $a = [3, 2, 1, 4, 2, 2]$.

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From steps $10$ and $11$, we can deduce that the the multiset $\left\{a_3, a_5, a_6\right\}$ must be $\left\{2, 2, 1\right\}$.

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From steps $8$ and $9$, the multiset $\left\{a_1, a_5, a_6\right\}$ must be either $\left\{4, 4, 1\right\}$ or $\left\{3, 2, 2\right\}$.

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As $\left\{a_3, a_5, a_6\right\}$ and $\left\{a_1, a_5, a_6\right\}$ share $a_5$ and $a_6$, we conclude that $a_5 = a_6 = 2$, as well as $a_1 = 3$, $a_3 = 1$.

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From steps $6$ and $7$, we know that $a_5 = a_6 = 2$, and $a_4$, $a_5$ and $a_6$ cannot form a non-degenerate triangle, hence $a_4 = 4$.

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With all the known information, only $a_2 = 2$ satisfies the queries made in steps $2$, $3$, $4$, $5$, $12$ and $13$.

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In the third example, one array that satisfies the queries is $[1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]$.

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样例

Input #1
3

63
Output #1
? 1 2 3

! -1
InputCopy OutputCopy
Input #2
6

0

0

0

63

15

135
Output #2
? 1 2 3

? 2 3 4

? 4 5 6

? 1 5 6

? 3 5 6

? 1 2 4

! 3 2 1 4 2 2
InputCopy OutputCopy
Input #3
15

3

3

3

3

3

0
Output #3
? 1 2 3

? 4 6 7

? 8 9 10

? 11 12 13

? 13 14 15

? 4 5 6

! -1
InputCopy OutputCopy
Input #4
15

3

15

0

3

3

3
Output #4
? 1 2 3

? 3 4 5

? 4 5 6

? 7 8 9

? 10 11 12

? 13 14 15

! 1 1 1 2 2 4 1 1 1 1 1 1 1 1 1 1
InputCopy OutputCopy
Input #5
10

3

48

3

48

63

0
Output #5
? 1 3 5

? 4 6 8

? 1 5 9

? 6 8 10

? 4 2 6

? 7 10 8

! 1 3 1 2 1 2 4 2 1 2
InputCopy OutputCopy
题目信息
题号
1847E
时间限制
2 s
内存限制
256 MB
标签
暴力
组合数学
模拟
交互题
数学
概率论

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