#include <bits/stdc++.h>
using namespace std;
typedef long long lld;
const int MOD = 1e9 + 7;
int fpow(int n, int k)
{
if(k == 0) return 1;
if(k % 2){
return 1ll * n * fpow(n, k - 1) % MOD;
}
int h = fpow(n, k / 2);
return 1ll * h * h % MOD;
}
inline int inv(int n)
{
return 1ll * fpow(n, MOD - 2) % MOD;
}
inline void mult(int& a, int b)
{
a = 1ll * a * b % MOD;
}
inline int mult2(int a, int b)
{
return 1ll * a * b % MOD;
}
inline void sub(int& a, int b)
{
a = ((a - b) % MOD + MOD) % MOD;
}
inline int rational(int a, int b)
{
return 1ll * a * inv(b) % MOD;
}
inline void add(int &a, int b)
{
a = ((a + b) % MOD + MOD) % MOD;
}
int main()
{
int n, k;
cin >> n >> k;
if(n%2){
cout << 0 << '\n';
return 0;
}
int ans = 1;
for(int i = 0; i < n / 2; ++i){
mult(ans, n - i);
mult(ans, inv(i + 1));
}
mult(ans, inv(n/2 + 1));
cout << ans << '\n';
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Incorrect |
65 ms |
1720 KB |
Output isn't correct |
2 |
Halted |
0 ms |
0 KB |
- |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Halted |
0 ms |
0 KB |
- |