41| 快速乘

代码实现

#include <bits/stdc++.h>
using namespace std;

#define int long long

int a, b, p;

int qmul(int a, int b, int p)
{
	int ret = 0;
	while(b)
	{
		if(b & 1) ret = (ret + a) % p;
		a = (a + a) % p;
		b >>= 1;
	}
	return ret;
}
signed main()
{
	cin >> a >> b >> p;
	cout << qmul(a, b, p);
	return 0;
}