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题库练习 Optimal Number Permutation

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A10225 | $Optimal Number Permutation$

时间限制1s

内存限制256MB

通过 / 提交0/0

题目描述

You have array $a$ that contains all integers from $1$ to $n$ twice. You can arbitrary permute any numbers in $a$ . Let number $i$ be in positions $x_{i},y_{i}$ ( $x_{i}<y_{i}$ ) in the permuted array $a$ . Let's define the value $d_{i}=y_{i}-x_{i}$ — the distance between the positions of the number $i$ . Permute the numbers in array $a$ to minimize the value of the sum ![](/uploads/acgo/image/281681cceebf646b_522cf2a6d7b1.jpeg).

输入格式

The only line contains integer $n$ ( $1<=n<=5·10^{5}$ ).

输出格式

Print $2n$ integers — the permuted array $a$ that minimizes the value of the sum $s$ .

输入输出样例

输入 #1

输出 #1

1 1 2 2

输入 #2

输出 #2

1 1

C++ 编辑器

输入

输出