#include <iostream>
using namespace std;
#define rep(i, a, b) for (ll i = (a); i <= (b); ++i)
using ll = long long;
const int N = 3 << 10, M = 1e9 + 7;
ll dp[N][N];
void add(ll& x, ll y) {
x = x + y;
if (x < 0) x += M;
if (M <= x) x -= M;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int h, w; cin >> h >> w;
rep(i, 0, h) dp[i][0] = 1;
rep(j, 0, w) dp[0][j] = 1;
rep(i, 1, h) {
rep(j, 1, w) {
auto add = [&](ll x) {
dp[i][j] += x;
if (M <= dp[i][j]) dp[i][j] -= M;
};
if (i != 1) add(i * (i - 1) / 2 % M * dp[i - 2][j - 1] % M);
add(4 * i * dp[i - 1][j - 1] % M);
add(dp[i][j - 1]);
if (j != 1) add(i * (j - 1) % M * dp[i - 1][j - 2]);
}
}
cout << (dp[h][w] + M - 1) % M;
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
384 KB |
Output is correct |
2 |
Correct |
5 ms |
384 KB |
Output is correct |
3 |
Correct |
5 ms |
512 KB |
Output is correct |
4 |
Correct |
5 ms |
1152 KB |
Output is correct |
5 |
Incorrect |
5 ms |
896 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
5 ms |
384 KB |
Output is correct |
2 |
Correct |
5 ms |
384 KB |
Output is correct |
3 |
Correct |
5 ms |
512 KB |
Output is correct |
4 |
Correct |
5 ms |
1152 KB |
Output is correct |
5 |
Incorrect |
5 ms |
896 KB |
Output isn't correct |
6 |
Halted |
0 ms |
0 KB |
- |