oj.uz

Submission #478344

# Submission time Handle Problem Language Result Execution time Memory
478344 2021-10-07T05:32:52 Z daongocha Tents (JOI18_tents) C++14
100 / 100
 138 ms 117548 KB 
#include <bits/stdc++.h>

#define int long long

#define fileopen(a, b) freopen(((std::string)a + ".inp").c_str(), "r", stdin); freopen(((std::string)b + ".out").c_str(), "w", stdout);
#define fileopen1(a) freopen(((std::string)a + ".inp").c_str(), "r", stdin); freopen(((std::string)a + ".out").c_str(), "w", stdout);

#ifdef PICHU_LOCAL_DEF
	#include <chrono>
#endif

using namespace std;

const int MAXN = 3005, MOD = 1e9 + 7;
int C[MAXN][MAXN]; 
int dp[MAXN][MAXN];
int fact[MAXN * 5];
int inv[MAXN * 5];

int power(int x, int n) {
	int res = 1;
	while (n) {
		if (n & 1) (res *= x) %= MOD;
		(x *= x) %= MOD;
		n >>= 1;
	}
	return res;
}

void prec() {
	for (int i = 0; i < MAXN; i++)
		for (int j = 0; j <= i; j++) {
			if (j == 0 || j == i) C[i][j] = 1;
			else C[i][j] = (C[i - 1][j - 1] + C[i - 1][j]) % MOD;
		}
}

signed main() {
	#ifdef PICHU_LOCAL_DEF
		chrono::steady_clock::time_point begin = std::chrono::steady_clock::now();
	#endif

	#ifndef PICHU_LOCAL_DEF
		//fileopen1("LAH");
	#endif

	ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

	fact[0] = 1;
	inv[0] = 1;
	for (int i = 1; i < 10000; i++) fact[i] = fact[i - 1] * i % MOD, inv[i] = power(power(2, i), MOD - 2);

	for (int r = 0; r < MAXN; r++) {
		for (int c = 0; c < MAXN; c++) {
			if (!r || !c) dp[r][c] = 1;
			else dp[r][c] = (r * 4 * dp[r - 1][c - 1] + dp[r][c - 1]) % MOD;
		}
	}

	prec();

	int n, m;
	cin >> n >> m;

	int ans = 0, cnt = 0;
	for (int rows = 0; rows <= min(m / 2, n); rows++) {
		int max_cols = m - 2 * rows;
		int rem = n - rows; 
		for (int cols = 0; cols <= min(rem / 2, max_cols); cols++) {
			int emp_col = m - 2 * rows - cols;
			int emp_row = n - 2 * cols - rows;
			ans += C[n][rows] * C[m][2 * rows] % MOD * fact[2 * rows] % MOD * inv[rows] % MOD * inv[cols] % MOD * C[max_cols][cols] % MOD * C[rem][2 * cols] % MOD * fact[2 * cols] % MOD * dp[emp_col][emp_row] % MOD;	
			ans %= MOD;
		}
	}

	cout << (ans - 1 + MOD) % MOD << '\n';

	#ifdef PICHU_LOCAL_DEF
		chrono::steady_clock::time_point end = std::chrono::steady_clock::now();
		std::cout << std::endl;
		std::cout << "Time difference = " << chrono::duration_cast<chrono::milliseconds> (end - begin).count() << "[ms]" << std::endl;
	#endif
}

Compilation message

tents.cpp: In function 'int main()':
tents.cpp:65:15: warning: unused variable 'cnt' [-Wunused-variable]
   65 |  int ans = 0, cnt = 0;
      |               ^~~

Subtask #1
48.0 / 48.0

# Verdict Execution time Memory Grader output
1 Correct 106 ms 117444 KB Output is correct
2 Correct 105 ms 117428 KB Output is correct
3 Correct 102 ms 117524 KB Output is correct
4 Correct 105 ms 117444 KB Output is correct
5 Correct 106 ms 117464 KB Output is correct
6 Correct 105 ms 117496 KB Output is correct
7 Correct 101 ms 117516 KB Output is correct
8 Correct 103 ms 117496 KB Output is correct
9 Correct 101 ms 117424 KB Output is correct
10 Correct 106 ms 117444 KB Output is correct
11 Correct 103 ms 117520 KB Output is correct
12 Correct 104 ms 117504 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 106 ms 117444 KB Output is correct
2 Correct 105 ms 117428 KB Output is correct
3 Correct 102 ms 117524 KB Output is correct
4 Correct 105 ms 117444 KB Output is correct
5 Correct 106 ms 117464 KB Output is correct
6 Correct 105 ms 117496 KB Output is correct
7 Correct 101 ms 117516 KB Output is correct
8 Correct 103 ms 117496 KB Output is correct
9 Correct 101 ms 117424 KB Output is correct
10 Correct 106 ms 117444 KB Output is correct
11 Correct 103 ms 117520 KB Output is correct
12 Correct 104 ms 117504 KB Output is correct
13 Correct 99 ms 117476 KB Output is correct
14 Correct 110 ms 117496 KB Output is correct
15 Correct 125 ms 117444 KB Output is correct
16 Correct 102 ms 117444 KB Output is correct
17 Correct 104 ms 117440 KB Output is correct
18 Correct 104 ms 117488 KB Output is correct
19 Correct 125 ms 117468 KB Output is correct
20 Correct 117 ms 117548 KB Output is correct
21 Correct 113 ms 117444 KB Output is correct
22 Correct 114 ms 117444 KB Output is correct
23 Correct 102 ms 117452 KB Output is correct
24 Correct 138 ms 117444 KB Output is correct
25 Correct 125 ms 117456 KB Output is correct
26 Correct 128 ms 117444 KB Output is correct
27 Correct 132 ms 117544 KB Output is correct