AtCoder Grand Contest 064
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⌀ 996
原题
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Problem Statement

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You are given a positive integer $N$. Print an integer sequence of length $L \coloneqq N(N+1)/2$, $A = (A_1, A_2, \ldots, A_L)$, that satisfies all of the following conditions.

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  • $A$ contains exactly $i$ occurrences of $i$ for every $i = 1, 2, \ldots, N$.
  • $1 \leq |A_i - A_{i+1}| \leq 2$ for every $i = 1, 2, \ldots, L$. Here, $A_{L+1}$ means $A_1$.
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It can be proved that, under the Constraints of this problem, there is always an integer sequence $A$ of length $L$ that satisfies all of the above conditions.

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Constraints

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  • $3 \leq N \leq 1000$
  • $N$ is an integer.
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Input

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The input is given from Standard Input in the following format:

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N

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Output

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Print the elements of $A$, separated by spaces, in the following format:

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A_1 A_2 \ldots A_L

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If multiple integer sequences $A$ of length $L$ satisfy the conditions in the problem statement, any one of them is accepted.

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样例

Input #1
4
Output #1
1 3 4 2 4 3 4 2 4 3
The integer sequence $A = (1, 3, 4, 2, 4, 3, 4, 2, 4, 3)$ contains exactly one $1$, two $2$s, three $3$s, and four $4$s, satisfying the first condition. The second condition is also satisfied, as follows: - $|A_1 - A_2| = |1 - 3| = 2$ - $|A_2 - A_3| = |3 - 4| = 1$ - $|A_3 - A_4| = |4 - 2| = 2$ - $|A_4 - A_5| = |2 - 4| = 2$ - $|A_5 - A_6| = |4 - 3| = 1$ - $|A_6 - A_7| = |3 - 4| = 1$ - $|A_7 - A_8| = |4 - 2| = 2$ - $|A_8 - A_9| = |2 - 4| = 2$ - $|A_9 - A_{10}| = |4 - 3| = 1$ - $|A_{10} - A_1| = |3 - 1| = 2$
题目信息
题号
agc064_a
时间限制
2 s
内存限制
1024 MB

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