添加链接描述

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+8;
int arr[N],ans[N];
int main(){int n;scanf("%d",&n);for(int i=1;i<=n;i++){scanf("%d",&arr[i]);}sort(arr+1,arr+1+n);int l=1,r=n;for(int i=1;i<=n;i++){if(i&1){ans[i]=arr[r--];}else ans[i]=arr[l++];}int res=0;res=n+1>>1;cout<<res-1<<endl;for(int i=1;i<=n;i++){cout<<ans[i]<<" ";}cout<<endl;return 0;
}