#include <iostream>
#include <fstream>
#include <algorithm>
/*
Time O(M * N ^ 2)
Memory O(M * N)
*/
constexpr int MOD = (int)1e9 + 7;
constexpr int MAXN = 3000;
constexpr int MAXM = 3000;
int dp[MAXM + 1][MAXN + 1];
int comb[2 * MAXN + 1][2 * MAXN + 1];
int pow2[2 * MAXN + 1], fact[2 * MAXN + 1];
int counter[MAXM];
inline void add(int& x, int y) {
x += y;
if (x >= MOD)
x -= MOD;
}
void prec(int N, int M) {
for (int i = 0; i <= 2 * N; i++) {
comb[i][0] = 1;
for (int j = 1; j <= i; j++) {
add(comb[i][j], comb[i - 1][j]);
add(comb[i][j], comb[i - 1][j - 1]);
}
}
for (int i = 0; i < 2 * N; i++) {
counter[i % M]++;
}
pow2[0] = fact[0] = 1;
for (int i = 1; i <= 2 * N; i++) {
pow2[i] = (2LL * pow2[i - 1]) % MOD;
fact[i] = (1LL * i * fact[i - 1]) % MOD;
}
}
int main() {
std::istream& fin = std::cin;
std::ostream& fout = std::cout;
int N, M;
fin >> N >> M;
prec(N, M);
dp[M][N] = 1;
int used = 0;
for (int rem = M; rem > 0; rem--) {
used += counter[rem];
for (int pairs = 0; pairs <= N; pairs++) {
if (dp[rem][pairs] == 0)
continue;
int need = counter[rem - 1];
for (int p = 0; p <= pairs; p++) {
int others = 2 * N - 2 * pairs - used;
if (need > p + others || need < p)
continue;
int current = (1LL * comb[pairs][p] * comb[others][need - p]) % MOD;
// current = (1LL * current * pow2[p]) % MOD;
current = (1LL * current * dp[rem][pairs]) % MOD;
add(dp[rem - 1][pairs - p], current);
}
}
}
int answer = (1LL * dp[0][0] * pow2[N]) % MOD;
for (int rem = 0; rem < M; rem++) {
answer = (1LL * answer * fact[counter[rem]]) % MOD;
}
fout << answer << "\n";
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
1 ms |
2392 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
4444 KB |
Output is correct |
5 |
Correct |
1 ms |
4700 KB |
Output is correct |
6 |
Correct |
1 ms |
4440 KB |
Output is correct |
7 |
Correct |
1 ms |
4444 KB |
Output is correct |
8 |
Correct |
1 ms |
4444 KB |
Output is correct |
9 |
Correct |
1 ms |
4584 KB |
Output is correct |
10 |
Correct |
1 ms |
4440 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
1 ms |
2392 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
4444 KB |
Output is correct |
5 |
Correct |
1 ms |
4700 KB |
Output is correct |
6 |
Correct |
1 ms |
4440 KB |
Output is correct |
7 |
Correct |
1 ms |
4444 KB |
Output is correct |
8 |
Correct |
1 ms |
4444 KB |
Output is correct |
9 |
Correct |
1 ms |
4584 KB |
Output is correct |
10 |
Correct |
1 ms |
4440 KB |
Output is correct |
11 |
Correct |
1 ms |
6716 KB |
Output is correct |
12 |
Correct |
1 ms |
6492 KB |
Output is correct |
13 |
Correct |
1 ms |
6492 KB |
Output is correct |
14 |
Correct |
1 ms |
6492 KB |
Output is correct |
15 |
Correct |
1 ms |
6492 KB |
Output is correct |
16 |
Correct |
1 ms |
6492 KB |
Output is correct |
17 |
Correct |
1 ms |
6492 KB |
Output is correct |
18 |
Correct |
1 ms |
6492 KB |
Output is correct |
19 |
Correct |
1 ms |
6488 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
1 ms |
2392 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
4444 KB |
Output is correct |
5 |
Correct |
1 ms |
4700 KB |
Output is correct |
6 |
Correct |
1 ms |
4440 KB |
Output is correct |
7 |
Correct |
1 ms |
4444 KB |
Output is correct |
8 |
Correct |
1 ms |
4444 KB |
Output is correct |
9 |
Correct |
1 ms |
4584 KB |
Output is correct |
10 |
Correct |
1 ms |
4440 KB |
Output is correct |
11 |
Correct |
1 ms |
6716 KB |
Output is correct |
12 |
Correct |
1 ms |
6492 KB |
Output is correct |
13 |
Correct |
1 ms |
6492 KB |
Output is correct |
14 |
Correct |
1 ms |
6492 KB |
Output is correct |
15 |
Correct |
1 ms |
6492 KB |
Output is correct |
16 |
Correct |
1 ms |
6492 KB |
Output is correct |
17 |
Correct |
1 ms |
6492 KB |
Output is correct |
18 |
Correct |
1 ms |
6492 KB |
Output is correct |
19 |
Correct |
1 ms |
6488 KB |
Output is correct |
20 |
Correct |
1 ms |
9048 KB |
Output is correct |
21 |
Correct |
1 ms |
9308 KB |
Output is correct |
22 |
Correct |
5 ms |
14172 KB |
Output is correct |
23 |
Correct |
1 ms |
13148 KB |
Output is correct |
24 |
Correct |
3 ms |
12124 KB |
Output is correct |
25 |
Correct |
3 ms |
14172 KB |
Output is correct |
26 |
Correct |
2 ms |
11100 KB |
Output is correct |
27 |
Correct |
4 ms |
14428 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
1 ms |
2392 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
4444 KB |
Output is correct |
5 |
Correct |
1 ms |
4700 KB |
Output is correct |
6 |
Correct |
1 ms |
4440 KB |
Output is correct |
7 |
Correct |
1 ms |
4444 KB |
Output is correct |
8 |
Correct |
1 ms |
4444 KB |
Output is correct |
9 |
Correct |
1 ms |
4584 KB |
Output is correct |
10 |
Correct |
1 ms |
4440 KB |
Output is correct |
11 |
Correct |
1 ms |
6716 KB |
Output is correct |
12 |
Correct |
1 ms |
6492 KB |
Output is correct |
13 |
Correct |
1 ms |
6492 KB |
Output is correct |
14 |
Correct |
1 ms |
6492 KB |
Output is correct |
15 |
Correct |
1 ms |
6492 KB |
Output is correct |
16 |
Correct |
1 ms |
6492 KB |
Output is correct |
17 |
Correct |
1 ms |
6492 KB |
Output is correct |
18 |
Correct |
1 ms |
6492 KB |
Output is correct |
19 |
Correct |
1 ms |
6488 KB |
Output is correct |
20 |
Correct |
1 ms |
9048 KB |
Output is correct |
21 |
Correct |
1 ms |
9308 KB |
Output is correct |
22 |
Correct |
5 ms |
14172 KB |
Output is correct |
23 |
Correct |
1 ms |
13148 KB |
Output is correct |
24 |
Correct |
3 ms |
12124 KB |
Output is correct |
25 |
Correct |
3 ms |
14172 KB |
Output is correct |
26 |
Correct |
2 ms |
11100 KB |
Output is correct |
27 |
Correct |
4 ms |
14428 KB |
Output is correct |
28 |
Correct |
5 ms |
16476 KB |
Output is correct |
29 |
Correct |
13 ms |
18548 KB |
Output is correct |
30 |
Correct |
19 ms |
19548 KB |
Output is correct |
31 |
Correct |
5 ms |
21080 KB |
Output is correct |
32 |
Correct |
14 ms |
23640 KB |
Output is correct |
33 |
Correct |
24 ms |
25484 KB |
Output is correct |
34 |
Correct |
46 ms |
30804 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
1 ms |
2396 KB |
Output is correct |
2 |
Correct |
1 ms |
2392 KB |
Output is correct |
3 |
Correct |
0 ms |
2396 KB |
Output is correct |
4 |
Correct |
1 ms |
4444 KB |
Output is correct |
5 |
Correct |
1 ms |
4700 KB |
Output is correct |
6 |
Correct |
1 ms |
4440 KB |
Output is correct |
7 |
Correct |
1 ms |
4444 KB |
Output is correct |
8 |
Correct |
1 ms |
4444 KB |
Output is correct |
9 |
Correct |
1 ms |
4584 KB |
Output is correct |
10 |
Correct |
1 ms |
4440 KB |
Output is correct |
11 |
Correct |
1 ms |
6716 KB |
Output is correct |
12 |
Correct |
1 ms |
6492 KB |
Output is correct |
13 |
Correct |
1 ms |
6492 KB |
Output is correct |
14 |
Correct |
1 ms |
6492 KB |
Output is correct |
15 |
Correct |
1 ms |
6492 KB |
Output is correct |
16 |
Correct |
1 ms |
6492 KB |
Output is correct |
17 |
Correct |
1 ms |
6492 KB |
Output is correct |
18 |
Correct |
1 ms |
6492 KB |
Output is correct |
19 |
Correct |
1 ms |
6488 KB |
Output is correct |
20 |
Correct |
1 ms |
9048 KB |
Output is correct |
21 |
Correct |
1 ms |
9308 KB |
Output is correct |
22 |
Correct |
5 ms |
14172 KB |
Output is correct |
23 |
Correct |
1 ms |
13148 KB |
Output is correct |
24 |
Correct |
3 ms |
12124 KB |
Output is correct |
25 |
Correct |
3 ms |
14172 KB |
Output is correct |
26 |
Correct |
2 ms |
11100 KB |
Output is correct |
27 |
Correct |
4 ms |
14428 KB |
Output is correct |
28 |
Correct |
5 ms |
16476 KB |
Output is correct |
29 |
Correct |
13 ms |
18548 KB |
Output is correct |
30 |
Correct |
19 ms |
19548 KB |
Output is correct |
31 |
Correct |
5 ms |
21080 KB |
Output is correct |
32 |
Correct |
14 ms |
23640 KB |
Output is correct |
33 |
Correct |
24 ms |
25484 KB |
Output is correct |
34 |
Correct |
46 ms |
30804 KB |
Output is correct |
35 |
Correct |
24 ms |
46684 KB |
Output is correct |
36 |
Correct |
301 ms |
61884 KB |
Output is correct |
37 |
Correct |
23 ms |
45904 KB |
Output is correct |
38 |
Correct |
138 ms |
52052 KB |
Output is correct |
39 |
Correct |
225 ms |
53588 KB |
Output is correct |
40 |
Correct |
420 ms |
72276 KB |
Output is correct |