hust新人赛模拟20150407 C

C - C

Time Limit:1000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u

Submit Status

Description

Permutationp is an ordered set of integers p₁,   p₂,   ...,   p_n, consisting of n distinct positive integers not larger than n. We'll denote asn the length of permutation p₁,   p₂,   ...,   p_n.

Your task is to find such permutation p of length n, that the group of numbers |p₁ - p₂|, |p₂ - p₃|, ..., |p_n - 1 - p_n| 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 Input

Input

3 2

Output

1 3 2

Input

3 1

Output

1 2 3

Input

5 2

Output

1 3 2 4 5

Hint

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

题意是说找到找到一组n个由1..n组成的数列，且每个数字只出现一次

满足每相邻的两项的差的绝对值一共有k种。

找规律即可。不好描述，直接上代码吧。

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
     int n,k;
     int tmp,p;
     const int N=1E5+7;
     int a[N];

int main()
{

     scanf("%d %d",&n,&k);
     for ( int i = 1; i <= n ; i++ )
        a[i] = i;
        tmp = k;
        p = 1;
     for ( int i = 2 ; i <= k+1  ; i++)
     {
         a[i] = a[i-1] + tmp*p;
         tmp--;
         p=p*-1;
     }
     for ( int i = 1 ; i < n ; i++ )
        printf("%d ",a[i]);
    printf("%d",a[n]);

    return 0;
}