[AHOI 2009] 同类分布

[题目链接]

https://www.lydsy.com/JudgeOnline/problem.php?id=1799

[算法]

数位DP

[代码]

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

int i;
long long a,b,ans;
long long f[][MAXS + ][MAXS + ][];

inline long long calc(long long x,int p)
{
        int i,j,k,t,len;
        int a[];
        len = ;
        while (x > )
        {
                a[++len] = x % ;
                x /= ;
        }
        reverse(a + ,a + len + );
        memset(f,,sizeof(f));
        f[][][][] = ;
        for (i = ; i < len; i++)
        {
                for (j = ; j <= p; j++)
                {
                        for (k = ; k < p; k++)
                        {
                                if (!f[i][j][k][] && !f[i][j][k][]) continue;
                                for (t = ; t <= ; t++)
                                {
                                        if (j + t <= p) f[i + ][j + t][(k *  + t) % p][] += f[i][j][k][];
                                        if (t < a[i + ] && j + t <= p) f[i + ][j + t][(k *  + t) % p][] += f[i][j][k][];
                                        if (t == a[i + ] && j + t <= p) f[i + ][j + t][(k *  + t) % p][] += f[i][j][k][];
                                }
                        }
                }
        }
        return f[len][p][][] + f[len][p][][];
}

int main()
{

        scanf("%lld%lld",&a,&b);
        for (i = ; i <= MAXS; i++) ans += calc(b,i) - calc(a - ,i);
        printf("%lld\n",ans);    

        return ;
}