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P1313 [NOIP2011 提高组] 计算系数

https://www.luogu.com.cn/record/79904335
This commit is contained in:
Baoshuo Ren 2022-07-17 11:25:44 +08:00
parent 7e7e4f27a1
commit e94a89bd34
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A

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Luogu/P1313/P1313.cpp Normal file
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#include <iostream>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1005;
const int mod = 1e4 + 7;
int a, b, k, n, m;
int fac[N], inv[N];
int binpow(int a, int b) {
int res = 1;
a %= mod;
while (b) {
if (b & 1) res = 1ll * res * a % mod;
a = 1ll * a * a % mod;
b >>= 1;
}
return res;
}
inline int C(int n, int m) {
return 1ll * fac[n] * inv[m] % mod * inv[n - m] % mod;
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
fac[0] = 1;
for (int i = 1; i <= 1000; i++) {
fac[i] = 1ll * fac[i - 1] * i % mod;
}
inv[0] = inv[1] = 1;
for (int i = 2; i <= 1000; i++) {
inv[i] = static_cast<long long>(mod - (mod / i)) * inv[mod % i] % mod;
}
for (int i = 2; i <= 1000; i++) {
inv[i] = static_cast<long long>(inv[i - 1]) * inv[i] % mod;
}
cin >> a >> b >> k >> n >> m;
cout << static_cast<long long>(C(k, n)) * binpow(a, n) % mod * binpow(b, m) % mod << endl;
return 0;
}