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Time Limit: 1 s Memory Limit: 512 MB Total points: 100

#16520. Permutation

统计

题目背景

$1+2+3+\cdots+n=\dfrac {n\times (n+1)} 2$。

题目描述

给定一个正整数 $n$。

我们定义,对于一个 $1$ 到 $n$ 的排列 $\{x_n\}$, $f(\{x_n\})=\max\limits_{i=1}^{n}(x_i+x_{(i \bmod n)+1})-\min\limits_{i=1}^{n}(x_i+x_{(i \bmod n)+1})$。

你需要构造一个 $1$ 到 $n$ 的排列 $\{p_n\}$,使得对于任意一个 $1$ 到 $n$ 的排列 $\{q_n\}$,都有 $f(\{p_n\})\le f(\{q_n\})$,并输出你构造的排列 $\{p_n\}$。

输入格式

一个正整数 $n$。

输出格式

$n$ 个整数,表示你构造的排列 $\{p_n\}$,之间用空格分隔。

所有满足条件的输出均可通过。

样例 1 输入

4

样例 1 输出

1 4 2 3

样例 1 解释

$f(\{1,4,2,3\})=2$,可以证明对于任意一个 $1$ 到 $n$ 的排列 $\{q_n\}$,都有 $f(\{1,4,2,3\})\le f(\{q_n\})$。

当然,$\{1,3,2,4\},\{3,1,4,2\},\{4,1,3,2\}$ 等也为合法的排列 $\{p_n\}$。

数据范围

对于所有数据,$3 \le n \le 10^6$。

本题采用捆绑测试。

子任务编号 分值 $n \le$ 特殊性质
$1$ $20$ $8$
$2$ $25$ $10^6$ 保证 $n \equiv 0 \pmod 2$
$3$ $25$ $10^6$ 保证 $n \equiv 1 \pmod 2$
$4$ $30$ $10^6$

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