慢速乘模板

Posted 2022-11-29 allinoo

	//慢速乘模板
	ll a, b;
	cin >> a >> b;
	ll r=0;
	while (b)
	
		if (b & 1)
		
			r += a;
		
		a <<= 1;//乘二运算
		b >>= 1;
	
	cout << r << endl;