#include<bits/stdc++.h>
using namespace std;
#define f first
#define s second
const int maxn = 4e3+5;
const int mod = 1e9+7;
typedef long long ll;
int n, m;
ll dp[maxn][maxn][2];
int pos[maxn];
ll f(int i, int j, int k){
if(i == n)return k==0;
else if(dp[i][j][k] != -1)return dp[i][j][k];
else{
int gap = pos[i]-i;
dp[i][j][k] = 0;
int p2 = n/2 - j - (i-j)/2;
if(p2)dp[i][j][k]+=f(i+1, j+1, k)*p2*2%mod;
if(j)dp[i][j][k]+=f(i+1, j-1, k)*j%mod;
if(gap >= 2)dp[i][j][k]+=f(i+2, j, k^1)*p2*2%mod*(gap-1)%mod;
dp[i][j][k]%=mod;
//cout << i << " " << j << " " << k << " " << dp[i][j][k] << endl;
return dp[i][j][k];
}
}
int main(){
memset(dp, -1, sizeof(dp));
cin >> n >> m;
n*=2;
int crr = 0;
for(int i = 0; i < m-n%m; i++){
int st = crr+n/m;
for(int j = 0; j < n/m; j++)pos[crr++]=st;
}
for(int i = 0; i < n%m; i++){
int st = crr+n/m+1;
for(int j = 0; j < n/m+1; j++)pos[crr++]=st;
}
ll ans = f(0, 0, 0)- f(0, 0, 1);
if(ans < 0)ans+=mod;
cout << ans;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
90 ms |
251392 KB |
Output is correct |
2 |
Correct |
87 ms |
251328 KB |
Output is correct |
3 |
Correct |
90 ms |
251308 KB |
Output is correct |
4 |
Correct |
97 ms |
251332 KB |
Output is correct |
5 |
Correct |
91 ms |
251288 KB |
Output is correct |
6 |
Correct |
89 ms |
251360 KB |
Output is correct |
7 |
Correct |
104 ms |
251548 KB |
Output is correct |
8 |
Correct |
96 ms |
251312 KB |
Output is correct |
9 |
Correct |
99 ms |
251288 KB |
Output is correct |
10 |
Correct |
87 ms |
251388 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
90 ms |
251392 KB |
Output is correct |
2 |
Correct |
87 ms |
251328 KB |
Output is correct |
3 |
Correct |
90 ms |
251308 KB |
Output is correct |
4 |
Correct |
97 ms |
251332 KB |
Output is correct |
5 |
Correct |
91 ms |
251288 KB |
Output is correct |
6 |
Correct |
89 ms |
251360 KB |
Output is correct |
7 |
Correct |
104 ms |
251548 KB |
Output is correct |
8 |
Correct |
96 ms |
251312 KB |
Output is correct |
9 |
Correct |
99 ms |
251288 KB |
Output is correct |
10 |
Correct |
87 ms |
251388 KB |
Output is correct |
11 |
Correct |
90 ms |
251424 KB |
Output is correct |
12 |
Correct |
90 ms |
251352 KB |
Output is correct |
13 |
Correct |
101 ms |
251332 KB |
Output is correct |
14 |
Correct |
93 ms |
251356 KB |
Output is correct |
15 |
Correct |
94 ms |
251300 KB |
Output is correct |
16 |
Correct |
91 ms |
251400 KB |
Output is correct |
17 |
Correct |
88 ms |
251304 KB |
Output is correct |
18 |
Correct |
89 ms |
251292 KB |
Output is correct |
19 |
Correct |
92 ms |
251332 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
90 ms |
251392 KB |
Output is correct |
2 |
Correct |
87 ms |
251328 KB |
Output is correct |
3 |
Correct |
90 ms |
251308 KB |
Output is correct |
4 |
Correct |
97 ms |
251332 KB |
Output is correct |
5 |
Correct |
91 ms |
251288 KB |
Output is correct |
6 |
Correct |
89 ms |
251360 KB |
Output is correct |
7 |
Correct |
104 ms |
251548 KB |
Output is correct |
8 |
Correct |
96 ms |
251312 KB |
Output is correct |
9 |
Correct |
99 ms |
251288 KB |
Output is correct |
10 |
Correct |
87 ms |
251388 KB |
Output is correct |
11 |
Correct |
90 ms |
251424 KB |
Output is correct |
12 |
Correct |
90 ms |
251352 KB |
Output is correct |
13 |
Correct |
101 ms |
251332 KB |
Output is correct |
14 |
Correct |
93 ms |
251356 KB |
Output is correct |
15 |
Correct |
94 ms |
251300 KB |
Output is correct |
16 |
Correct |
91 ms |
251400 KB |
Output is correct |
17 |
Correct |
88 ms |
251304 KB |
Output is correct |
18 |
Correct |
89 ms |
251292 KB |
Output is correct |
19 |
Correct |
92 ms |
251332 KB |
Output is correct |
20 |
Correct |
91 ms |
251304 KB |
Output is correct |
21 |
Correct |
107 ms |
251348 KB |
Output is correct |
22 |
Correct |
101 ms |
251384 KB |
Output is correct |
23 |
Correct |
108 ms |
251404 KB |
Output is correct |
24 |
Correct |
100 ms |
251492 KB |
Output is correct |
25 |
Correct |
95 ms |
251432 KB |
Output is correct |
26 |
Correct |
96 ms |
251332 KB |
Output is correct |
27 |
Correct |
126 ms |
251356 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
90 ms |
251392 KB |
Output is correct |
2 |
Correct |
87 ms |
251328 KB |
Output is correct |
3 |
Correct |
90 ms |
251308 KB |
Output is correct |
4 |
Correct |
97 ms |
251332 KB |
Output is correct |
5 |
Correct |
91 ms |
251288 KB |
Output is correct |
6 |
Correct |
89 ms |
251360 KB |
Output is correct |
7 |
Correct |
104 ms |
251548 KB |
Output is correct |
8 |
Correct |
96 ms |
251312 KB |
Output is correct |
9 |
Correct |
99 ms |
251288 KB |
Output is correct |
10 |
Correct |
87 ms |
251388 KB |
Output is correct |
11 |
Correct |
90 ms |
251424 KB |
Output is correct |
12 |
Correct |
90 ms |
251352 KB |
Output is correct |
13 |
Correct |
101 ms |
251332 KB |
Output is correct |
14 |
Correct |
93 ms |
251356 KB |
Output is correct |
15 |
Correct |
94 ms |
251300 KB |
Output is correct |
16 |
Correct |
91 ms |
251400 KB |
Output is correct |
17 |
Correct |
88 ms |
251304 KB |
Output is correct |
18 |
Correct |
89 ms |
251292 KB |
Output is correct |
19 |
Correct |
92 ms |
251332 KB |
Output is correct |
20 |
Correct |
91 ms |
251304 KB |
Output is correct |
21 |
Correct |
107 ms |
251348 KB |
Output is correct |
22 |
Correct |
101 ms |
251384 KB |
Output is correct |
23 |
Correct |
108 ms |
251404 KB |
Output is correct |
24 |
Correct |
100 ms |
251492 KB |
Output is correct |
25 |
Correct |
95 ms |
251432 KB |
Output is correct |
26 |
Correct |
96 ms |
251332 KB |
Output is correct |
27 |
Correct |
126 ms |
251356 KB |
Output is correct |
28 |
Correct |
121 ms |
251412 KB |
Output is correct |
29 |
Correct |
135 ms |
251500 KB |
Output is correct |
30 |
Correct |
113 ms |
251412 KB |
Output is correct |
31 |
Correct |
110 ms |
251448 KB |
Output is correct |
32 |
Correct |
110 ms |
251488 KB |
Output is correct |
33 |
Correct |
115 ms |
251520 KB |
Output is correct |
34 |
Correct |
132 ms |
251588 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
90 ms |
251392 KB |
Output is correct |
2 |
Correct |
87 ms |
251328 KB |
Output is correct |
3 |
Correct |
90 ms |
251308 KB |
Output is correct |
4 |
Correct |
97 ms |
251332 KB |
Output is correct |
5 |
Correct |
91 ms |
251288 KB |
Output is correct |
6 |
Correct |
89 ms |
251360 KB |
Output is correct |
7 |
Correct |
104 ms |
251548 KB |
Output is correct |
8 |
Correct |
96 ms |
251312 KB |
Output is correct |
9 |
Correct |
99 ms |
251288 KB |
Output is correct |
10 |
Correct |
87 ms |
251388 KB |
Output is correct |
11 |
Correct |
90 ms |
251424 KB |
Output is correct |
12 |
Correct |
90 ms |
251352 KB |
Output is correct |
13 |
Correct |
101 ms |
251332 KB |
Output is correct |
14 |
Correct |
93 ms |
251356 KB |
Output is correct |
15 |
Correct |
94 ms |
251300 KB |
Output is correct |
16 |
Correct |
91 ms |
251400 KB |
Output is correct |
17 |
Correct |
88 ms |
251304 KB |
Output is correct |
18 |
Correct |
89 ms |
251292 KB |
Output is correct |
19 |
Correct |
92 ms |
251332 KB |
Output is correct |
20 |
Correct |
91 ms |
251304 KB |
Output is correct |
21 |
Correct |
107 ms |
251348 KB |
Output is correct |
22 |
Correct |
101 ms |
251384 KB |
Output is correct |
23 |
Correct |
108 ms |
251404 KB |
Output is correct |
24 |
Correct |
100 ms |
251492 KB |
Output is correct |
25 |
Correct |
95 ms |
251432 KB |
Output is correct |
26 |
Correct |
96 ms |
251332 KB |
Output is correct |
27 |
Correct |
126 ms |
251356 KB |
Output is correct |
28 |
Correct |
121 ms |
251412 KB |
Output is correct |
29 |
Correct |
135 ms |
251500 KB |
Output is correct |
30 |
Correct |
113 ms |
251412 KB |
Output is correct |
31 |
Correct |
110 ms |
251448 KB |
Output is correct |
32 |
Correct |
110 ms |
251488 KB |
Output is correct |
33 |
Correct |
115 ms |
251520 KB |
Output is correct |
34 |
Correct |
132 ms |
251588 KB |
Output is correct |
35 |
Correct |
245 ms |
251700 KB |
Output is correct |
36 |
Correct |
261 ms |
251724 KB |
Output is correct |
37 |
Correct |
271 ms |
251616 KB |
Output is correct |
38 |
Correct |
241 ms |
251708 KB |
Output is correct |
39 |
Correct |
232 ms |
251780 KB |
Output is correct |
40 |
Correct |
327 ms |
251780 KB |
Output is correct |