Diverse Permutation - CodeForces 482 A 水题

A. 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 asn the 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.

题意：排列n个数，使得相邻两个数的差一共有k种。

思路：我们不难想出最多有n-1种差，假设n是10的话，那么就是1、10、2、9、3、8、4、7、5、6这么排，减少k的话，只需要让后面的按顺序使得差为1即可。

AC代码如下：

#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<cmath>using namespace std;typedef long long ll;int main(){    int T,t,n,m,i,j,k,l,r;    scanf("%d%d",&n,&k);    l=1;r=n;    for(i=1;i<=k;i++)    {        if(i&1)        {            printf("%d ",l);            l++;        }        else        {            printf("%d ",r);            r--;        }    }    if(!(i&1))    for(i=l;i<=r;i++)       printf("%d ",i);    else    for(i=r;i>=l;i--)       printf("%d ",i);    printf("\n");}