self 同类分布 HYSBZ - 1799

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

枚举各位数字之和 然后数位DP 将数值对所枚举的数字之和取模

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long ll;
const int maxn=20;
const int maxm=200;

ll dp[maxn][maxm][maxm];
int pre[maxn];
int bit[maxn];

void init(int mod)
{
    int i;
    pre[0]=1;
    for(i=1;i<=19;i++){
        pre[i]=(10*pre[i-1])%mod;
    }
}

ll dfs(int pos,int sta1,int sta2,int mod,int limit)
{
    ll res;
    int up,i,tmp;
    if(pos==-1){
        if(sta1==0&&sta2==0) return 1;
        else return 0;
    }
    if(!limit&&dp[pos][sta1][sta2]!=-1) return dp[pos][sta1][sta2];
    if(limit) up=bit[pos];
    else up=9;
    res=0;
    for(i=0;i<=up;i++){
        if(sta2-i>=0){
            tmp=(sta1+i*pre[pos])%mod;
            res+=dfs(pos-1,tmp,sta2-i,mod,limit&&i==bit[pos]);
        }
    }
    if(!limit) dp[pos][sta1][sta2]=res;
    return res;
}

ll solve(ll val)
{
    ll res;
    int n,i;
    n=0;
    while(val>0){
        bit[n++]=val%10;
        val/=10;
    }
    res=0;
    for(i=1;i<=9*n;i++){
        memset(dp,-1,sizeof(dp));
        init(i);
        res+=dfs(n-1,0,i,i,1);
    }
    return res;
}

int main()
{
    ll l,r;
    scanf("%lld%lld",&l,&r);
    printf("%lld\n",solve(r)-solve(l-1));
    return 0;
}

//1 999