【HDU 3037】Saving Beans Lucas定理模板
http://acm.hdu.edu.cn/showproblem.php?pid=3037
Lucas定理模板。
现在才写,noip滚粗前兆QAQ
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
int jc[100003];
int p;
int ipow(int x, int b) {
ll t = 1, w = x;
while (b) {
if (b & 1) t = t * w % p;
w = w * w % p;
b >>= 1;
}
return (int) t;
}
int Lucas(int n, int m) {
int a, b, ret = 1;
while (n && m) {
a = n % p; b = m % p;
if (a < b) return 0;
ret = (int) (1ll * ret * jc[a] % p * ipow((int) (1ll * jc[a - b] * jc[b] % p), p - 2) % p);
n /= p; m /= p;
}
return ret;
}
int main() {
int T, n, m;
scanf("%d", &T);
while (T--) {
scanf("%d%d%d", &n, &m, &p);
jc[0] = 1;
for (int i = 1; i < p; ++i)
jc[i] = (int) (1ll * jc[i - 1] * i % p);
printf("%d\n", Lucas(n + m, n));
}
return 0;
}
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