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 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|, ..., |p

n - 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.

解題思路： 題目大意是說要求構造一個n個數的排列，要求相鄰兩數的差值的絕對值保證是k個不同的數。 再次被神奇的數學所折服·····我們先構造1~n-k這些數，然後構造2~n這些數。 完整程式碼：

#include <functional>
#include <algorithm>
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <numeric>
#include <cstring>
#include <climits>
#include <cassert>
#include <complex>
#include <cstdio>
#include <string>
#include <vector>
#include <bitset>
#include <queue>
#include <stack>
#include <cmath>
#include <ctime>
#include <list>
#include <set>
#include <map>
using namespace std;

#pragma comment(linker, "/STACK:102400000,102400000")

typedef long long LL;
typedef double DB;
typedef unsigned uint;
typedef unsigned long long uLL;

/** Constant List .. **/ //{

const int MOD = int(1e9)+7;
const int INF = 0x3f3f3f3f;
const LL INFF = 0x3f3f3f3f3f3f3f3fLL;
const DB EPS = 1e-9;
const DB OO = 1e20;
const DB PI = acos(-1.0); //M_PI;


int main()
{
    #ifdef DoubleQ
    freopen("in.txt","r",stdin);
    #endif
    int n , k;
    while(~scanf("%d%d",&n,&k))
    {
        int tmp = n;
        int key = n - k;
        for(int i = 1 ; i <= key ; i ++)
            printf("%d ", i );
        key++;
        while(key <= tmp)
        {
            printf("%d " , tmp--);
            if(key <= tmp)
                printf("%d ",key ++);
            else
                break;
        }
        printf("\n");
    }
}