Little Elephant and Elections小象选举

　　在我正看着roll神的博客的时候发现了自己的错误

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>
using namespace std;
typedef long long LL;
LL ans;
const LL mod= 1000000007 ;
LL dp[100][100];
LL up[1000];
LL Hash[100];
LL dfs(LL now,LL sum,LL flag)
{
    if(sum>ans) return 0;
    if(now<=0) return sum==ans;
    if(!flag&&~dp[now][sum]) return dp[now][sum];
    LL limit= flag? up[now]:9,ret=0;
    for(LL i = 0;i<= limit;i++){
        if(i==4||i==7) ret+=dfs(now-1,sum+1,flag&&i==limit);
        else ret+=dfs(now-1,sum,flag&&i==limit);
    }
    return flag? ret : dp[now][sum]=ret;
}
LL  solve(LL x)
{
    LL len=0;
    while(x){
        up[++len]=x%10;
        x/=10;
    }
    return dfs(len,0,1);
}

LL len;
LL ans1=0;
void gao(LL dep,LL left,LL w)
{
    w%=mod;
    if(dep==0){
        ans1+=w;ans1%=mod;return ;
    }
    for(LL i= 0;i<=left;i++){
        if(Hash[i])gao(dep-1,left-i,w*Hash[i]--),Hash[i]++;
    }
}
int main()
{
    LL n;
    cin>>n;
    memset(Hash,0,sizeof(Hash));
    for(ans=0 ;ans<10;ans++){
        memset(dp,-1,sizeof(dp));//需要重新初始化。
        Hash[ans]= solve(n) - solve(0);
    }
    len=10;
    while(!Hash[len]) len--;
    for(LL i = 1;i<=len;i++)
        if(Hash[i])gao(6,i-1,Hash[i]);
    cout<<ans1<<endl;
    return 0;
}