排列之和 (Add Again,UVa 11076)

#include <iostream>
#include <string.h>
#include <string>
#include <fstream>
#include <algorithm>
#include <stdio.h>
#include <vector>
#include <queue>
#include <set>
#include <cmath>
using namespace std;
const double eps = 1e-8;
const int INF=0x7fffffff;
unsigned long long uINF = ~0LL;
#define MAXN 10000007
typedef unsigned long long LL;
LL vis[MAXN];
LL prime[MAXN];

void sieve(LL n)
{
    LL m=(LL)sqrt(n+0.5);
    memset(vis,0,sizeof(vis));
    for(LL i=2;i<=m;i++)if(!vis[i])
    for(LL j=i*i;j<=n;j+=i)vis[j]=1;
}

LL gen_prime(LL n)
{
    sieve(n);
    LL c=0;
    for(LL i=2;i<=n;i++)if(!vis[i])
        prime[c++]=i;
    return c;
}

LL gcd(LL a,LL b)
{
    return b==0?a:gcd(b,a%b);
}

int main()
{
    int N;
    int a[13];a[0]=1;
    for(int i=1;i<13;i++){a[i]=a[i-1]*i;}

    LL num[12];
    while(scanf("%d",&N),N)
    {
        int hash[11];
        LL t=0;
        memset(hash,0,sizeof(hash));
        for(int i=0;i<N;i++)
        {
        scanf("%lld",&num[i]);
        hash[num[i]]++;
        t=t*10+1;
        }
        LL ans=0;
        LL sum=0;
            int temp=a[N];
            for(int i=0;i<N;i++){sum+=num[i];}
            for(int i=0;i<10;i++)temp/=a[hash[i]];
            ans+=sum*t*temp/N;
            printf("%lld
",ans);
    }

    return 0;
}

卡在计算 排列的个数上了好久……=。=