【CODEFORCES】C. Diverse Permutation

C. 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.

题解：这一题就是简单构造，1，n-1，2……构造k个不同的差就可以了。

#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

int n,k;

int main()
{
scanf("%d%d",&n,&k);
//build
if (k==1)
{
for (int i=1;i<=n;i++) printf("%d ",i);
return 0;
}
else
{
int last=1,t=n,f=1,p=1;
printf("%d ",last);
while (k!=1)
{
last=last+(--t)*f;
f=f*(-1);
printf("%d ",last);
p++; k--;
}
if (f>=0) for (int i=p-p/2+1;i<=n-p/2;i++) printf("%d ",i);
else for (int i=n-p/2;i>=p-p/2+1;i--) printf("%d ",i);
}
return 0;
}