Submission #1170876

#	Time	Username	Problem	Language	Result	Execution time	Memory
1170876		chikien2009	Tents (JOI18_tents)	C++20	100 / 100	79 ms	70728 KiB

tents

#include <bits/stdc++.h>

using namespace std;

void setup()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int n, m;
long long fac[3001], inv[3001], f[3001][3001], g[3001][3001];
const long long mod = 1e9 + 7;

inline long long Bpow(long long inp, long long ind)
{
    long long res = 1;
    do
    {
        res = (ind & 1 ? (res * inp) % mod : res);
        inp = (inp * inp) % mod;
    } while (ind >>= 1);
    return res;
}

inline long long C(int k, int n)
{
    return (((fac[n] * inv[k]) % mod) * inv[n - k]) % mod;
}

int main()
{
    setup();

    fac[0] = 1;
    inv[0] = Bpow(fac[0], mod - 2);
    for (int i = 1; i <= 3000; ++i)
    {
        fac[i] = (i * fac[i - 1]) % mod;
        inv[i] = Bpow(fac[i], mod - 2);
    }
    cin >> n >> m;
    for (int i = 1; i <= n; ++i)
    {
        for (int j = 1; j <= m; ++j)
        {
            f[i][j] = (f[i - 1][j - 1] + 1) * 4;
            if (2 <= j)
            {
                f[i][j] += (f[i - 1][j - 2] + 1) * (j - 1);
            }
            if (2 <= i)
            {
                f[i][j] += (f[i - 2][j - 1] + 1) * (i - 1);
            }
            f[i][j] += 4 * (f[i - 1][j - 1] + 1) * (i - 1);
            if (2 <= j)
            {
                f[i][j] += f[i][j - 1];
            }
            if (2 <= j)
            {
                f[i][j] += (f[i - 1][j - 2] + 1) * (i - 1) * (j - 1);
            }
            if (3 <= i)
            {
                f[i][j] += (f[i - 2][j - 1] + 1) * C(2, i - 1);
            }
            f[i][j] %= mod;
        }
    }
    cout << f[n][m];
    return 0;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52