Codeforces Round 865 (Div. 2)
B
Grid Reconstruction
Codeforces
1000
原题
← AC →
翻译中…

Consider a $2 \times n$ grid, where $n$ is an even integer. You may place the integers $1, 2, \ldots, 2n$ on the grid, using each integer exactly once.

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A path is a sequence of cells achieved by starting at $(1, 1)$, then repeatedly walking either downwards or to the right, and stopping when $(2, n)$ is reached. The path should not extend beyond the grid.

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The cost of a path is the alternating sum of the numbers written on the cells in a path. That is, let the numbers written on the cells be $a_1, a_2, \ldots, a_k$ (in the order that it is visited), the cost of the path is $a_1 - a_2 + a_3 - a_4 + \ldots = \sum_{i=1}^k a_i \cdot (-1)^{i+1}$.

翻译中…

Construct a way to place the integers $1, 2, \ldots, 2n$ on the grid, such that the minimum cost over all paths from $(1, 1)$ to $(2, n)$ is maximized. If there are multiple such grids that result in the maximum value, output any of them.

翻译中…

Input

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The first line contains a single integer $t$ ($1 \leq t \leq 1000$) — the number of test cases. The description of test cases follows.

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The first and the only line of each test case contains a single integer $n$ ($2 \leq n \leq 10^5$, $n$ is even) — the number of the columns in the grid.

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It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$.

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Output

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For each test case, output $2$ lines, each containing $n$ integers — the desired grid. If there are multiple solutions, output any of them.

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Note

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In the first test case, there are only two paths from cell $(1, 1)$ to cell $(2, 2)$. Their costs are $3-1+4=6$ and $3-2+4=5$. Then the minimum cost is $5$, which is the maximum possible value.

翻译中…

In the second test case, there are four paths from cell $(1, 1)$ to cell $(2, 4)$. Their costs are $8-1+5-3+7=16$, $8-2+5-3+7=15$, $8-2+6-3+7=16$, and $8-2+6-4+7=15$. Then the minimum value is $15$, which is the maximum possible value.

翻译中…

样例

Input #1
3
2
4
6
Output #1
3 2
1 4
8 2 6 4
1 5 3 7
11 5 9 1 7 3
6 10 2 8 4 12
InputCopy OutputCopy
题目信息
题号
1816B
时间限制
1 s
内存限制
256 MB
标签
构造
贪心

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。