Submission #1273105

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273105		trvhung	Tents (JOI18_tents)	C++20	100 / 100	120 ms	77460 KiB

tents

#include <bits/stdc++.h>
// #include <ext/rope>
// #include <ext/pb_ds/assoc_container.hpp>

// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;

// #define   ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define            ll long long
#define           ull unsigned long long
#define            ld long double
#define            pb push_back
#define  bit(mask, i) ((mask >> i) & 1)
#define            el '\n'
#define             F first
#define             S second

template <class X, class Y> bool maximize(X &x, const Y &y) { return (x < y ? x = y, 1 : 0); }
template <class X, class Y> bool minimize(X &x, const Y &y) { return (x > y ? x = y, 1 : 0); }

const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
const int MULTI = 0;
const ld eps = 1e-9;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0}; // R D L U
const int ddx[4] = {-1, 1, 1, -1}, ddy[4] = {1, 1, -1, -1}; // UR DR DL UL
const char cx[4] = {'R', 'D', 'L', 'U'};
const ll base = 31;
const int nMOD = 2;
const ll mods[] = {(ll)1e9 + 10777, (ll)1e9 + 19777, (ll)1e9 + 3, (ll)1e9 + 3777};

const int N = 3e3 + 5;
int h, w, dp[N][N], f[N][N], g[N][N];
int fac[N], ifac[N];

int binpow(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1) res = 1LL * res * a % MOD;
        a = 1LL * a * a % MOD;
        b >>= 1;
    }
    return res;
}

void precalc() {
	fac[0] = 1;
	for (int i = 1; i < N; ++i)
		fac[i] = 1LL * fac[i - 1] * i % MOD;

	ifac[N - 1] = binpow(fac[N - 1], MOD - 2);
	for (int i = N - 2; i >= 0; --i)
		ifac[i] = 1LL * ifac[i + 1] * (i + 1) % MOD;
}

int C(int n, int k) {
	if (n < k) return 0;
	return 1LL * fac[n] * ifac[k] % MOD * ifac[n - k] % MOD; 
}

void solve() {
	cin >> h >> w;

	precalc();

	for (int i = 0; i <= w; ++i) {
		f[i][0] = 1;
		for (int j = 1; j <= min(h, i / 2); ++j)
			f[i][j] = 1LL * f[i][j - 1] * C(i - 2 * (j - 1), 2) % MOD;
	}

	for (int i = 0; i <= h; ++i) {
		g[i][0] = 1;
		for (int j = 1; j <= min(w, i / 2); ++j)
			g[i][j] = 1LL * g[i][j - 1] * C(i - 2 * (j - 1), 2) % MOD;
	}

	for (int i = 1; i <= h; ++i)
		for (int j = 1; j <= w; ++j) { 
			dp[i][j] = (dp[i - 1][j] + 1LL * j * 4 % MOD * ((i == 1 || j == 1) ? 1 : dp[i - 1][j - 1]) % MOD) % MOD;
			if (i > 1 && j > 1) (dp[i][j] += 4 * j) %= MOD;
		}

	int res = 0;
	for (int row2 = 0; row2 <= min(h, w / 2); ++row2) {
		int comb = C(h, row2);
		comb = 1LL * comb * f[w][row2] % MOD;

		int tmp = comb;
		for (int col2 = 0; col2 <= min(w - 2 * row2, (h - row2) / 2); ++col2) {
			comb = 1LL * comb * C(w - 2 * row2, col2) % MOD;
			comb = 1LL * comb * g[h - row2][col2] % MOD;

			int remain_h = h - row2 - 2 * col2;
			int remain_w = w - col2 - 2 * row2;

			if (remain_h && remain_w) {
				if (remain_h < h || remain_w < w) 
					(res += comb) %= MOD;
				comb = 1LL * comb * dp[remain_h][remain_w] % MOD;
			}

			(res += comb) %= MOD;
			comb = tmp;
		}
	}

	cout << res;
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    if (!MULTI) solve();
    else {
        int test; cin >> test;
        while (test--) solve();
    }
    
    return 0;
}

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