HDU 3652 —— B-number

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
using namespace std;

int len;
int a[12], b[12];
int dp[12][2][2][13];

int dfs(int u, bool is1, bool have, int mod, bool limit)
{
    if(u < 1)    return have && mod ==0;
    
    if(!limit && dp[u][is1][have][mod] != -1)    return dp[u][is1][have][mod];
    
    int maxn = limit ? a[u] : 9;
    int ret = 0;
    
    for(int i=0; i<=maxn; i++) {
        b[u] = i;
        ret += dfs(u-1, i==1, have||is1&&i==3, (mod*10%13+i)%13, limit&&i==maxn);
    }
    if(!limit)    dp[u][is1][have][mod] = ret;
    return ret;
}

int f(int n)
{
    len=0;
    while(n) {
        a[++len] = n%10;
        n /= 10;
    }
    return dfs(len, 0, 0, 0, 1);
}

int main ()
{
    int n;
    memset(dp, -1, sizeof(dp));
    while(scanf("%d", &n) != EOF) {
        printf("%d\n", f(n));
    }
    
    return 0;
}