[杭电]Number Sequence

题目： http://acm.hdu.edu.cn/showproblem.php?pid=1005

代码：

#include <iostream>
#include <string>
using namespace std;

int res[50];

int main()
{
	int A, B, n;
	res[1] = 1;
	res[2] = 1;
	while (cin >> A >> B >> n)
	{
		if (A == 0 && B == 0 && n == 0)
		{
			break;
		}
		
		int temp;
		// minimize A,B
		A = A % 7;
		B = B % 7;

		// Because f(n-1) and f(n-2) are in 0..6.
		//So the function's max cycle is 49
		for (int i = 3; i <= 49; i++)
		{
			res[i] = (A*res[i - 1] + B*res[i - 2]) % 7;
		}
		n = n % 49;
		if (n == 0)
		{
			cout << res[49] << endl;
		}
		else
		{
			cout << res[n] << endl;
		}
	}

	return 0;
}