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\n", ans);

    }

    return 0;

}

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