排列之和 (Add Again,UVa 11076)

 1 #include <iostream>
 2 #include <string.h>
 3 #include <string>
 4 #include <fstream>
 5 #include <algorithm>
 6 #include <stdio.h>
 7 #include <vector>
 8 #include <queue>
 9 #include <set>
10 #include <cmath>
11 using namespace std;
12 const double eps = 1e-8;
13 const int INF=0x7fffffff;
14 unsigned long long uINF = ~0LL;
15 #define MAXN 10000007
16 typedef unsigned long long LL;
17 LL vis[MAXN];
18 LL prime[MAXN];
19 
20 void sieve(LL n)
21 {
22     LL m=(LL)sqrt(n+0.5);
23     memset(vis,0,sizeof(vis));
24     for(LL i=2;i<=m;i++)if(!vis[i])
25     for(LL j=i*i;j<=n;j+=i)vis[j]=1;
26 }
27 
28 LL gen_prime(LL n)
29 {
30     sieve(n);
31     LL c=0;
32     for(LL i=2;i<=n;i++)if(!vis[i])
33         prime[c++]=i;
34     return c;
35 }
36 
37 LL gcd(LL a,LL b)
38 {
39     return b==0?a:gcd(b,a%b);
40 }
41 
42 int main()
43 {
44     int N;
45     int a[13];a[0]=1;
46     for(int i=1;i<13;i++){a[i]=a[i-1]*i;}
47 
48     LL num[12];
49     while(scanf("%d",&N),N)
50     {
51         int hash[11];
52         LL t=0;
53         memset(hash,0,sizeof(hash));
54         for(int i=0;i<N;i++)
55         {
56         scanf("%lld",&num[i]);
57         hash[num[i]]++;
58         t=t*10+1;
59         }
60         LL ans=0;
61         LL sum=0;
62             int temp=a[N];
63             for(int i=0;i<N;i++){sum+=num[i];}
64             for(int i=0;i<10;i++)temp/=a[hash[i]];
65             ans+=sum*t*temp/N;
66             printf("%lld
",ans);
67     }
68 
69     return 0;
70 }
卡在计算排列的个数上了好久……=。=