#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
using ll = long long;
using ld = long double;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define sz(x) (int)x.size()
#define endl '\n'
const int mod = 1e9 + 7;
const int inf = 2e9 + 5;
const ll linf = 9e18 + 5;
int n, m;
const int N = 3e3 + 5;
const int M = 3e3 + 5;
int dp[N][M];
int mull(int a, int b) {
return (1ll * a * b) % mod;
}
int c2(int n) {
return (1ll * n * (n - 1)) / 2;
}
void init() {
}
void input() {
cin >> n >> m;
}
void solve() {
for (int j = 0; j <= m; j++) {
dp[0][j] = 1;
}
for (int i = 1; i <= n; i++) {
for (int j = 0; j <= m; j++) {
dp[i][j] = dp[i - 1][j];
if (j >= 1) {
dp[i][j] += mull(mull(j, 4), dp[i - 1][j - 1]);
dp[i][j] %= mod;
}
if (i >= 2) {
dp[i][j] += mull(mull(j, i - 1), dp[i - 2][j - 1]);
dp[i][j] %= mod;
}
if (i >= 1 && j >= 2) {
dp[i][j] += mull(c2(j), dp[i - 1][j - 2]);
dp[i][j] %= mod;
}
}
}
cout << dp[n][m] - 1;
}
void output() {
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int number_of_testcases = 1;
//cin >> number_of_testcases;
while (number_of_testcases--) {
init();
input();
solve();
output();
}
return 0;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
340 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
1108 KB |
Output is correct |
5 |
Correct |
1 ms |
592 KB |
Output is correct |
6 |
Correct |
1 ms |
1224 KB |
Output is correct |
7 |
Correct |
1 ms |
716 KB |
Output is correct |
8 |
Correct |
2 ms |
1364 KB |
Output is correct |
9 |
Correct |
1 ms |
724 KB |
Output is correct |
10 |
Correct |
2 ms |
1620 KB |
Output is correct |
11 |
Correct |
1 ms |
340 KB |
Output is correct |
12 |
Correct |
2 ms |
1876 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
212 KB |
Output is correct |
2 |
Correct |
1 ms |
340 KB |
Output is correct |
3 |
Correct |
1 ms |
468 KB |
Output is correct |
4 |
Correct |
1 ms |
1108 KB |
Output is correct |
5 |
Correct |
1 ms |
592 KB |
Output is correct |
6 |
Correct |
1 ms |
1224 KB |
Output is correct |
7 |
Correct |
1 ms |
716 KB |
Output is correct |
8 |
Correct |
2 ms |
1364 KB |
Output is correct |
9 |
Correct |
1 ms |
724 KB |
Output is correct |
10 |
Correct |
2 ms |
1620 KB |
Output is correct |
11 |
Correct |
1 ms |
340 KB |
Output is correct |
12 |
Correct |
2 ms |
1876 KB |
Output is correct |
13 |
Correct |
1 ms |
336 KB |
Output is correct |
14 |
Correct |
4 ms |
9544 KB |
Output is correct |
15 |
Correct |
86 ms |
32724 KB |
Output is correct |
16 |
Correct |
6 ms |
2644 KB |
Output is correct |
17 |
Correct |
21 ms |
7884 KB |
Output is correct |
18 |
Correct |
27 ms |
11012 KB |
Output is correct |
19 |
Correct |
98 ms |
34540 KB |
Output is correct |
20 |
Correct |
83 ms |
29052 KB |
Output is correct |
21 |
Correct |
53 ms |
19788 KB |
Output is correct |
22 |
Correct |
62 ms |
22164 KB |
Output is correct |
23 |
Correct |
34 ms |
19656 KB |
Output is correct |
24 |
Correct |
149 ms |
35520 KB |
Output is correct |
25 |
Correct |
101 ms |
30744 KB |
Output is correct |
26 |
Correct |
133 ms |
33464 KB |
Output is correct |
27 |
Correct |
146 ms |
34624 KB |
Output is correct |