UVa 11076 - Add Again （排列之和　组合数学）

Input

Output

Sample Input Output for Sample Input

#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <string>
#include <map>
#include <cmath>
#include <queue>
#include <set>

using namespace std;

//#define WIN
#ifdef WIN
typedef __int64 LL;
#define iform "%I64d"
#define oform "%I64d\n"
#define oform1 "%I64d"
#else
typedef long long LL;
#define iform "%lld"
#define oform "%lld\n"
#define oform1 "%lld"
#endif

#define S64I(a) scanf(iform, &(a))
#define P64I(a) printf(oform, (a))
#define P64I1(a) printf(oform1, (a))
#define REP(i, n) for(int (i)=0; (i)<n; (i)++)
#define REP1(i, n) for(int (i)=1; (i)<=(n); (i)++)
#define FOR(i, s, t) for(int (i)=(s); (i)<=(t); (i)++)

const int INF = 0x3f3f3f3f;
const double eps = 10e-9;
const double PI = (4.0*atan(1.0));

int vis[10];
unsigned long long C[20][20];

void init(int n) {
memset(C, 0, sizeof(C));
C[0][0] = 1;
for(int i=1; i<=n; i++) {
C[i][0] = C[i][i] = 1;
for(int j=1; j<i; j++) {
C[i][j] = C[i-1][j-1] + C[i-1][j];
}
}
}

int main() {
int n;

init(15);
while(scanf("%d", &n) != EOF && n) {
int sum = 0;
memset(vis, 0, sizeof(vis));
for(int i=0; i<n; i++) {
int t;
scanf("%d", &t);
vis[t]++;
sum += t;
}
unsigned long long p10 = 1;
unsigned long long ans = 0;
for(int i=0; i<n; i++) {
for(int j=1; j<10; j++) if(vis[j]) {
vis[j]--;
int lev = n-1;
LL tt = 1;
for(int k=1; k<10; k++) if(vis[k]) {
tt *= C[lev][vis[k]];
lev -= vis[k];
}
ans += p10 * j * tt;
vis[j]++;
}
p10 *= 10;
}
cout<<ans<<endl;
}

return 0;
}