快速幂（积）模板

#include<iostream>
#include<algorithm>
using namespace std;
#define ll long long
int qmi(ll a, ll b, ll mod) {	//求 m^n%p，时间复杂度 O(logn)
	ll flag = 1;
	while (b) {
		if (b & 1)flag = (flag*a)%mod;
		a = (a*a) % mod;
		b = b >> 1;
	}
	return flag%mod;
}

int qji(ll a, ll b, ll mod) {	//求 m*n%p，时间复杂度 O(logn)
	ll flag = 0;
	while (b) {
		if (b & 1)flag = (flag + a) % mod;
		a = (a << 1) % mod;
		b = b >> 1;
	}
	return flag%mod;
}

int main() {
	ll a, b, c;
	cin >> a >> b >> c;
	cout << a << "^" << b << " mod " << c << "=" << qmi(a, b, c) << "\n";
	cout << a << "*" << b << " mod " << c << "=" << qji(a, b, c) << "\n";
	return 0;
}

原文地址：https://www.cnblogs.com/52dxer/p/10421595.html