hdu3652

基本的数位dp，需要记录前面除以13的余数。

#include <cstdio>

#include <cstring>

using namespace std;



#define D(x) x



const int MAX_DIGIT = 35;



int n, m;

int f[MAX_DIGIT];

int memoize[MAX_DIGIT][2][2][2][13];



void to_digits(int a)

{

    for (int i = 0; i < MAX_DIGIT; i++)

    {

        f[i] = a % 10;

        a /= 10;

    }

}



int dfs(int digit, bool less, bool contain, bool one, int remain)

{

    if (digit == -1)

    {

        return contain && !remain;

    }

    if (memoize[digit][less][contain][one][remain] != -1)

    {

        return memoize[digit][less][contain][one][remain];

    }

    int limit = less ? 9 : f[digit];

    int ret = 0;

    for (int i = 0; i <= limit; i++)

    {

        int new_remain = (remain * 10 + i) % 13;

        if (i == 3  && one)

        {

            ret += dfs(digit - 1, less || i < f[digit], true, false, new_remain);

            continue;

        }

        if (i == 1)

        {

            ret += dfs(digit - 1, less || i < f[digit], contain, true, new_remain);

            continue;

        }

        ret += dfs(digit - 1, less || i < f[digit], contain, false, new_remain);

    }

    memoize[digit][less][contain][one][remain] = ret;

    return ret;

}



int main()

{

    while (scanf("%d", &n) != EOF)

    {

        to_digits(n);

        memset(memoize, -1, sizeof(memoize));

        int ans = dfs(32, false, false, false, 0);

        printf("%d\n", ans);

    }

    return 0;

}

View Code