CodeForces 652B z-sort（构造）

题意：定义一个z排序，就是奇数位置满足ai<=a[i-1]，偶数位置满足ai>=a[i-1]，给你n个数，让你构造出来这个z排序的序列
思路：动手画画，显然一个小的一个大的就好了，那么排序一波，然后奇数位置从1开始放，偶数位置从(n+1)/2+1开始放，这样子扔下去的奇数位置一定小于等于偶数位置。

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <set>
#include <ctime>
#include <cmath>
#include <cctype>
using namespace std;
#define maxn 10010
#define LL long long
int cas=1,T;
int n,a[maxn],b[maxn];
int main()
{
scanf("%d",&n);
for (int i = 1;i<=n;i++)
scanf("%d",&a[i]);
sort(a+1,a+1+n);
int l = 1,r=(n+1)/2+1;
for (int i = 1;i<=n;i++)
{
if (i%2==1)
printf("%d ",a[l++]);
else
printf("%d ",a[r++]);
}
//freopen("in","r",stdin);
//scanf("%d",&T);
//printf("time=%.3lf",(double)clock()/CLOCKS_PER_SEC);
return 0;
}

Description

A student of z-school found a kind of sorting called z-sort. The array a with n elements
are z-sorted if two conditions hold:

ai ≥ ai - 1 for all even i,
ai ≤ ai - 1 for all odd i > 1.

For example the arrays [1,2,1,2] and [1,1,1,1] are z-sorted while the array [1,2,3,4] isn’t z-sorted.

Can you make the array z-sorted?

Input

The first line contains a single integer n (1 ≤ n ≤ 1000) — the number of elements in the array a.

The second line contains n integers ai (1 ≤ ai ≤ 109)
— the elements of the array a.

Output

If it's possible to make the array az-sorted print n space
separated integers ai — the elements after z-sort. Otherwise print the only word "Impossible".

Sample Input

Input

4
1 2 2 1

Output

1 2 1 2

Input

5
1 3 2 2 5

Output

1 5 2 3 2