80741 - 同测活动第4场提高组阅读程序2
统计题目(材料题)
1 #include <iostream>
2 using namespace std;
3 typedef long long ll;
4
5 ll fPow(ll a, ll b, ll mod) {
6 ll res = 1;
7 a %= mod;
8 while (b > 0) {
9 if (b & 1) res = (res * a) % mod;
10 a = (a * a) % mod;
11 b >>= 1;
12 }
13 return res;
14 }
15
16 int main() {
17 ll n, p;
18 cin >> n >> p;
19 if (n >= p) {
20 cout << 0 << endl;
21 return 0;
22 }
23 ll res = p - 1;
24 for (ll i = n + 1; i < p; i++)
25 res = (res * fPow(i, p - 2, p)) % p;
26
27 cout << res << endl;
28 return 0;
29 }
||
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