Codeforces Gym 100623J Problem J. Just Too Lucky 數位DP

題目傳送門：http://codeforces.com/gym/100623/attachments

題解：數位DP經典題目，先暴力一遍，把可能出現的各位數字和都跑一遍，然後就是經典數位DP了，記憶化搜索寫完的，詳見代碼

Code:

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

long long n,dp[15][110][110];
int dight[15];

long long dfs(int len,int sum,int mod,int div,bool flag)
{
    if(len==0)
        return (sum==div)&&(mod==0);
    if(dp[len][sum][mod]!=-1&&flag==0)
        return dp[len][sum][mod];
    long long s=0;
    int u=flag?dight[len]:9;
    for(int i=0;i<=u;i++)
        s+=dfs(len-1,sum+i,(mod*10+i)%div,div,flag&&i==u);
    return flag?s:dp[len][sum][mod]=s;
}

long long solve(long long n)
{
    long long ans=0;
    int cur=0;
    memset(dp,-1,sizeof(dp));
    while(n)
    {
        dight[++cur]=n%10;
        n/=10;
    }
    for(int i=1;i<=cur*9;i++)
    {
        memset(dp,-1,sizeof(dp));
        ans+=dfs(cur,0,0,i,1);
    }
    return ans;
}

int main()
{
    freopen("just.in","r",stdin);
    freopen("just.out","w",stdout);
    while(cin>>n)
        cout<<solve(n)<<endl;
    return 0;
}