#include <unordered_map>
#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>
#include <set>
typedef long long llong;
const int MAXN = 2000 + 10;
const int MOD = 1e9 + 7;
const int INF = 1e9;
int n, m;
int fact[MAXN];
int var[MAXN][MAXN];
int comb[MAXN][MAXN];
inline llong getKey(int idx, int zeros, int ones)
{
return 1LL * idx * MAXN * MAXN + zeros * MAXN + ones;
}
std::unordered_map <llong,int> dp;
int f(int idx, int zeros, int ones)
{
if (idx == 0)
{
return (zeros == 0 && ones == 0);
}
llong key = getKey(idx, zeros, ones);
if (dp.count(key))
{
return dp[key];
}
int res = 0;
int len = (2*n - idx + 1) / m + (idx != 1);
for (int addOnes = std::max(0, len - ones) ; addOnes <= std::min(len, zeros) ; ++addOnes)
{
res += (((((1LL * f(idx-1, zeros - addOnes, ones + 2*addOnes - len) * comb[len][addOnes]) % MOD) * var[zeros][addOnes]) % MOD) * var[ones][len - addOnes]) % MOD;
if (res >= MOD) res -= MOD;
}
return dp[key] = res;
}
void solve()
{
for (int i = 0 ; i <= n ; ++i)
{
comb[i][0] = 1;
}
fact[0] = 1;
for (int i = 1 ; i <= n ; ++i)
{
fact[i] = (1LL * fact[i-1] * i) % MOD;
}
for (int i = 1 ; i <= n ; ++i)
{
for (int j = 1 ; j <= i ; ++j)
{
comb[i][j] = comb[i-1][j] + comb[i-1][j-1];
if (comb[i][j] >= MOD) comb[i][j] -= MOD;
}
}
for (int i = 0 ; i <= n ; ++i)
{
for (int j = 0 ; j <= i ; ++j)
{
var[i][j] = (1LL * comb[i][j] * fact[j]) % MOD;
}
}
int ans = f(m, n, 0);
for (int i = 1 ; i <= n ; ++i)
{
ans *= 2;
ans %= MOD;
}
std::cout << ans << '\n';
}
void read()
{
std::cin >> n >> m;
}
void fastIO()
{
std::ios_base :: sync_with_stdio(0);
std::cout.tie(nullptr);
std::cin.tie(nullptr);
}
int main()
{
fastIO();
read();
solve();
return 0;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
1 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
1 ms |
340 KB |
Output is correct |
8 |
Correct |
1 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
1 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
1 ms |
340 KB |
Output is correct |
8 |
Correct |
1 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
1108 KB |
Output is correct |
12 |
Correct |
1 ms |
852 KB |
Output is correct |
13 |
Correct |
1 ms |
852 KB |
Output is correct |
14 |
Correct |
1 ms |
852 KB |
Output is correct |
15 |
Correct |
1 ms |
980 KB |
Output is correct |
16 |
Correct |
1 ms |
980 KB |
Output is correct |
17 |
Correct |
1 ms |
852 KB |
Output is correct |
18 |
Correct |
1 ms |
852 KB |
Output is correct |
19 |
Correct |
1 ms |
980 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
1 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
1 ms |
340 KB |
Output is correct |
8 |
Correct |
1 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
1108 KB |
Output is correct |
12 |
Correct |
1 ms |
852 KB |
Output is correct |
13 |
Correct |
1 ms |
852 KB |
Output is correct |
14 |
Correct |
1 ms |
852 KB |
Output is correct |
15 |
Correct |
1 ms |
980 KB |
Output is correct |
16 |
Correct |
1 ms |
980 KB |
Output is correct |
17 |
Correct |
1 ms |
852 KB |
Output is correct |
18 |
Correct |
1 ms |
852 KB |
Output is correct |
19 |
Correct |
1 ms |
980 KB |
Output is correct |
20 |
Correct |
1 ms |
1748 KB |
Output is correct |
21 |
Correct |
2 ms |
1748 KB |
Output is correct |
22 |
Correct |
5 ms |
3412 KB |
Output is correct |
23 |
Correct |
3 ms |
2516 KB |
Output is correct |
24 |
Correct |
4 ms |
3540 KB |
Output is correct |
25 |
Correct |
5 ms |
3284 KB |
Output is correct |
26 |
Correct |
2 ms |
2644 KB |
Output is correct |
27 |
Correct |
5 ms |
4180 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
1 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
1 ms |
340 KB |
Output is correct |
8 |
Correct |
1 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
1108 KB |
Output is correct |
12 |
Correct |
1 ms |
852 KB |
Output is correct |
13 |
Correct |
1 ms |
852 KB |
Output is correct |
14 |
Correct |
1 ms |
852 KB |
Output is correct |
15 |
Correct |
1 ms |
980 KB |
Output is correct |
16 |
Correct |
1 ms |
980 KB |
Output is correct |
17 |
Correct |
1 ms |
852 KB |
Output is correct |
18 |
Correct |
1 ms |
852 KB |
Output is correct |
19 |
Correct |
1 ms |
980 KB |
Output is correct |
20 |
Correct |
1 ms |
1748 KB |
Output is correct |
21 |
Correct |
2 ms |
1748 KB |
Output is correct |
22 |
Correct |
5 ms |
3412 KB |
Output is correct |
23 |
Correct |
3 ms |
2516 KB |
Output is correct |
24 |
Correct |
4 ms |
3540 KB |
Output is correct |
25 |
Correct |
5 ms |
3284 KB |
Output is correct |
26 |
Correct |
2 ms |
2644 KB |
Output is correct |
27 |
Correct |
5 ms |
4180 KB |
Output is correct |
28 |
Correct |
8 ms |
6996 KB |
Output is correct |
29 |
Correct |
16 ms |
9700 KB |
Output is correct |
30 |
Correct |
22 ms |
11876 KB |
Output is correct |
31 |
Correct |
8 ms |
7056 KB |
Output is correct |
32 |
Correct |
17 ms |
10200 KB |
Output is correct |
33 |
Correct |
46 ms |
13188 KB |
Output is correct |
34 |
Correct |
48 ms |
20324 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
340 KB |
Output is correct |
2 |
Correct |
0 ms |
340 KB |
Output is correct |
3 |
Correct |
0 ms |
340 KB |
Output is correct |
4 |
Correct |
1 ms |
340 KB |
Output is correct |
5 |
Correct |
1 ms |
340 KB |
Output is correct |
6 |
Correct |
0 ms |
340 KB |
Output is correct |
7 |
Correct |
1 ms |
340 KB |
Output is correct |
8 |
Correct |
1 ms |
340 KB |
Output is correct |
9 |
Correct |
0 ms |
340 KB |
Output is correct |
10 |
Correct |
0 ms |
340 KB |
Output is correct |
11 |
Correct |
1 ms |
1108 KB |
Output is correct |
12 |
Correct |
1 ms |
852 KB |
Output is correct |
13 |
Correct |
1 ms |
852 KB |
Output is correct |
14 |
Correct |
1 ms |
852 KB |
Output is correct |
15 |
Correct |
1 ms |
980 KB |
Output is correct |
16 |
Correct |
1 ms |
980 KB |
Output is correct |
17 |
Correct |
1 ms |
852 KB |
Output is correct |
18 |
Correct |
1 ms |
852 KB |
Output is correct |
19 |
Correct |
1 ms |
980 KB |
Output is correct |
20 |
Correct |
1 ms |
1748 KB |
Output is correct |
21 |
Correct |
2 ms |
1748 KB |
Output is correct |
22 |
Correct |
5 ms |
3412 KB |
Output is correct |
23 |
Correct |
3 ms |
2516 KB |
Output is correct |
24 |
Correct |
4 ms |
3540 KB |
Output is correct |
25 |
Correct |
5 ms |
3284 KB |
Output is correct |
26 |
Correct |
2 ms |
2644 KB |
Output is correct |
27 |
Correct |
5 ms |
4180 KB |
Output is correct |
28 |
Correct |
8 ms |
6996 KB |
Output is correct |
29 |
Correct |
16 ms |
9700 KB |
Output is correct |
30 |
Correct |
22 ms |
11876 KB |
Output is correct |
31 |
Correct |
8 ms |
7056 KB |
Output is correct |
32 |
Correct |
17 ms |
10200 KB |
Output is correct |
33 |
Correct |
46 ms |
13188 KB |
Output is correct |
34 |
Correct |
48 ms |
20324 KB |
Output is correct |
35 |
Correct |
47 ms |
22348 KB |
Output is correct |
36 |
Correct |
260 ms |
63932 KB |
Output is correct |
37 |
Correct |
45 ms |
22052 KB |
Output is correct |
38 |
Correct |
127 ms |
36028 KB |
Output is correct |
39 |
Correct |
203 ms |
46320 KB |
Output is correct |
40 |
Correct |
247 ms |
71028 KB |
Output is correct |