[SCOI 2007] 排列

[题目链接]

https://www.lydsy.com/JudgeOnline/problem.php?id=1072

[算法]

状压DP

[代码]

#include<bits/stdc++.h>
using namespace std;
#define MAXD 1000
const int MAXS = ;

int i,j,k,T,len,d,MASK;
char s[];
long long f[MAXS][MAXD];
long long ans;
long long fac[];
int cnt[];

int main()
{

    fac[] = ;
    for (i = ; i <= ; i++) fac[i] = fac[i-] * i;
    scanf("%d",&T);
    while (T--)
    {
        scanf("%s%d",&s,&d);
        len = strlen(s);
        MASK = ( << len) - ;
        memset(f,,sizeof(f));
        memset(cnt,,sizeof(cnt));
        for (i = ; i < len; i++) cnt[s[i] - '']++;
        f[][] = ;
        for (i = ; i <= MASK; i++)
        {
            for (j = ; j < d; j++)
            {
                for (k = ; k < len; k++)
                {
                    if ((i & ( << k)) == )
                        f[i | ( << k)][(j *  + s[k] - '') % d] += f[i][j];
                }
            }
        }
        ans = f[MASK][];
        for (i = ; i < ; i++) ans /= fac[cnt[i]];
        printf("%lld\n",ans);
    }

    return ;
}