Submission #1224913

#	Time	Username	Problem	Language	Result	Execution time	Memory
1224913		PenguinsAreCute	Tents (JOI18_tents)	C++17	0 / 100	0 ms	324 KiB

tents

#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
int exp(int a, int b) {
	return (b?1LL*exp(1LL*a*a%MOD,b/2)*(b&1?a:1)%MOD:1);
}
int solve(int h, int c) {
	int fact[3005];
	fact[0] = 1;
	for(int i=1;i<3005;i++)
		fact[i] = 1LL * fact[i-1] * i % MOD;
	int ans = MOD - 1;
	for(int r1=0;r1<=h;r1++)
		for(int r2=0;r2<=h-r1;r2++)
			for(int c2=0;c2<=c;c2++) {
				int c1 = (r1 + 2 * r2 - 2 * c2);
				if(c1 < 0 || c1 + c2 > c || c1 < 2 * r2)
					continue;
				ans = (ans + 1LL * fact[h] * fact[c] % MOD * exp(fact[r1], MOD-2) % MOD * exp(fact[r2], MOD-2) % MOD * exp(fact[h-r1-r2], MOD-2) % MOD * exp(fact[c1], MOD-2) % MOD * exp(fact[c2], MOD-2) % MOD * exp(fact[c-c1-c2], MOD-2) % MOD * fact[r1] % MOD * exp(fact[2*c2], MOD-2) % MOD * exp(fact[r1-2*c2], MOD-2) * fact[c1] % MOD * exp(fact[2*r2], MOD-2) * exp(fact[c1-2*r2], MOD-2) % MOD * exp(4,r1-2*c2) % MOD * fact[r1-2*c2]) % MOD;
			}
	return ans;
}
int main() {
	int h, c;
	cin >> h >> c;
	cout << solve(h, c);
}

• Subtask 1: 0 / 48
• Subtask 2: 0 / 52