HDU 3709 Balanced Number

发现只要Σa[i]*i%Σa[i]==0就可以。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
long long t,l,r,dp[20][1600][170],bit[20],ret=0;
void get_bit(long long x)
{
    ret=0;
    while (x) {bit[++ret]=x%10;x/=10;}
}
long long dfs(long long pos,long long val1,long long val2,bool flag)
{
    if (!pos)
    {
        if (!val2) return 1;
        return val1%val2==0;
    }
    if ((!flag) && (~dp[pos][val1][val2])) return dp[pos][val1][val2];
    long long ans=0,up=flag?bit[pos]:9;
    for (long long i=0;i<=up;i++)
        ans+=dfs(pos-1,val1+i*pos,val2+i,flag&&i==up);
    if (!flag) dp[pos][val1][val2]=ans;
    return ans;
}
long long work(long long x)
{
    if (x==-1) return 0;
    get_bit(x);    
    return dfs(ret,0,0,1);
}
int main()
{
    scanf("%lld",&t);memset(dp,-1,sizeof(dp));
    for (long long i=1;i<=t;i++)
    {
        scanf("%lld%lld",&l,&r);
        printf("%lld
",work(r)-work(l-1));    
    }    
    return 0;
}