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답안 #56611

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
56611 2018-07-12T03:22:19 Z ksun48 Tents (JOI18_tents) C++14
48 / 100
 2000 ms 3848 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long LL;

const LL MOD = 1000000007;

LL powmod(LL a, LL n){
	if(n == 0) return 1;
	if(n % 2) return (a * powmod(a, n-1)) % MOD;
	LL c = powmod(a, n/2);
	return (c * c) % MOD;
}

LL inv(LL a){
	return powmod(a, MOD-2);
}
LL fact[11000];
LL invfact[11000];

int main(){
	LL a, b;
	cin >> a >> b;
	fact[0] = invfact[0] = 1;
	for(LL i = 1; i < 11000; i++){
		fact[i] = (i * fact[i-1]) % MOD;
		invfact[i] = inv(fact[i]);
	}

	LL smth[a+1][b+1];
	for(int i = 0; i <= a; i++){
		for(int j = 0; j <= b; j++){
			LL cur = 0;
			for(int k = 0; k <= i && k <= j; k++){
				LL z = powmod(4,k);
				z = (z * invfact[k]) % MOD;
				z = (z * invfact[i-k]) % MOD;
				z = (z * invfact[j-k]) % MOD;
				cur = (cur + z) % MOD;
			}
			smth[i][j] = cur;
		}
	}

	LL ans = 0;
	for(LL c = 0; c <= a && c*2 <= b; c++){
		for(LL d = 0; c + 2*d <= a && c*2 + d <= b; d++){
			LL cur = (fact[a] * fact[b]) % MOD;
			cur = (cur * inv(powmod(2,c))) % MOD;
			cur = (cur * inv(powmod(2,d))) % MOD;
			cur = (cur * invfact[c]) % MOD;
			cur = (cur * invfact[d]) % MOD;
			cur = (cur * smth[a - c - 2*d][b - c*2 - d]) % MOD;
			ans = (ans + cur) % MOD;
		}
	}
	ans--;
	ans %= MOD;
	if(ans < 0) ans += MOD;
	cout << ans << '\n';
}

Subtask #1
48.0 / 48.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 692 KB Output is correct
2 Correct 8 ms 692 KB Output is correct
3 Correct 8 ms 736 KB Output is correct
4 Correct 6 ms 920 KB Output is correct
5 Correct 31 ms 1020 KB Output is correct
6 Correct 45 ms 1152 KB Output is correct
7 Correct 60 ms 1152 KB Output is correct
8 Correct 24 ms 1152 KB Output is correct
9 Correct 7 ms 1152 KB Output is correct
10 Correct 159 ms 1268 KB Output is correct
11 Correct 8 ms 1268 KB Output is correct
12 Correct 704 ms 2064 KB Output is correct

Subtask #2
0 / 52.0

# 결과 실행 시간 메모리 Grader output
1 Correct 8 ms 692 KB Output is correct
2 Correct 8 ms 692 KB Output is correct
3 Correct 8 ms 736 KB Output is correct
4 Correct 6 ms 920 KB Output is correct
5 Correct 31 ms 1020 KB Output is correct
6 Correct 45 ms 1152 KB Output is correct
7 Correct 60 ms 1152 KB Output is correct
8 Correct 24 ms 1152 KB Output is correct
9 Correct 7 ms 1152 KB Output is correct
10 Correct 159 ms 1268 KB Output is correct
11 Correct 8 ms 1268 KB Output is correct
12 Correct 704 ms 2064 KB Output is correct
13 Correct 7 ms 2064 KB Output is correct
14 Correct 8 ms 2064 KB Output is correct
15 Execution timed out 2064 ms 3848 KB Time limit exceeded
16 Halted 0 ms 0 KB -