hdu3555

基本的数位dp

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

#define D(x) x

const int MAX_DIGIT = 66;

long long n;
int f[MAX_DIGIT];
long long memoize[MAX_DIGIT][2][2][2];

void to_digits(long long a)
{
    for (int i = 0; i < MAX_DIGIT; i++)
    {
        f[i] = a % 10;
        a /= 10;
    }
}

long long dfs(int digit, bool less, bool contain, bool four)
{
    if (digit == -1)
    {
        return contain;
    }
    if (memoize[digit][less][contain][four] != -1)
    {
        return memoize[digit][less][contain][four];
    }
    int limit = less ? 9 : f[digit];
    long long ret = 0;
    for (int i = 0; i <= limit; i++)
    {
        if (four && i == 9)
        {
            ret += dfs(digit - 1, less || i < f[digit], true, false);
            continue;
        }
        if (i == 4)
        {
            ret += dfs(digit - 1, less || i < f[digit], contain, true);
            continue;
        }
        ret += dfs(digit - 1, less || i < f[digit], contain, false);
    }
    memoize[digit][less][contain][four] = ret;
    return ret;
}

int main()
{
    int t;
    scanf("%d", &t);
    while (t--)
    {
        scanf("%I64d", &n);
        to_digits(n);
        memset(memoize, -1, sizeof(memoize));
        long long ans = dfs(64, false, false, false);
        printf("%I64d
", ans);
    }
    return 0;
}