BZOJ 1679 [Usaco2005 Jan]Moo Volume 牛的呼声

#include <cstdio>
#include <algorithm>
#include <cmath>

int n;
int a[10005];
long long tot;

inline bool Read(int &ret){
    char c;
    int flag = 1;
    if(c=getchar(),c==EOF) return 0;
    while(c!=‘-‘ && (c<‘0‘||c>‘9‘)) c=getchar();
    flag = (c==‘-‘) ? -1 :1;
    ret = (c==‘-‘) ? 0 : (c-‘0‘);
    while(c=getchar(),c>=‘0‘&&c<=‘9‘) ret=ret*10+(c-‘0‘);
    ret*=flag;
    return 1;
}

int main(){
    Read(n);
    for(register int i=1;i<=n;++i){
        Read(a[i]);
        for(register int j=1;j<i;j++){
            tot+=abs(a[j]-a[i]);
        }
    }
    tot*=2;
    printf("%lld\n",tot);
    return 0;
}

#include <iostream>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#define LL long long
using namespace std;
int n,a[10005];
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
    scanf("%d",&a[i]);
    sort(a+1,a+1+n);
    LL ans=0;
    for (int i=2;i<=n;i++)
    {
        ans=ans+(long long )(a[i]-a[i-1])*((i-1)*(n+1-i));
    }
    cout<<ans*2<<endl;
    return 0;
}