Codeforces Round #275 (Div. 2) --C Diverse Permutation

题目链接：Diverse Permutation

Diverse Permutation

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Permutation p is an ordered set of integers p1,   p2,   ...,   pn, consisting of n distinct positive integers not larger than n. We'll denote as nthe length of permutation p1,   p2,   ...,   pn.

Your task is to find such permutation p of length n, that the group of numbers |p1 - p2|, |p2 - p3|, ..., |pn - 1 - pn| has exactly k distinct elements.

Input

The single line of the input contains two space-separated positive integers n, k (1 ≤ k < n ≤ 105).

Output

Print n integers forming the permutation. If there are multiple answers, print any of them.

Sample test(s)

input

3 2

output

1 3 2

input

3 1

output

1 2 3

input

5 2

output

1 3 2 4 5

Note

By |x| we denote the absolute value of number x.

大致题意：给一个n和k。让找到一种1~n的排列，满足，任意相邻两数之间的差值的绝对值必须为k个不同的值。

解题思路：开始用next_permutation(a, a+n)直接生成排列，然后判断，结果TLE到死。暴力枚举搞不定，那只能构造了。详见代码

AC代码：

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