HDU 1005测试数据有问题

Problem Description：

A number sequence is defined as follows:
f(1) = 1, f(2) = 1, f(n) = (A * f(n - 1) + B * f(n - 2)) mod 7.
Given A, B, and n, you are to calculate the value of f(n).

Input：
The input consists of multiple test cases. Each test case contains 3 integers A, B and n on a single line (1 <= A, B <= 1000, 1 <= n <= 100,000,000). Three zeros signal the end of input and this test case is not to be processed.


Output：

For each test case, print the value of f(n) on a single line.


Sample Input：

1 1 3
1 2 10
0 0 0

Sample Output：
2
5

import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		int n;
		int A,B;
		int[] f = new int[4];
				
		Scanner scan = new Scanner(System.in);
		A = scan.nextInt();
		B = scan.nextInt();
		n = scan.nextInt();
		
		while(A != 0 && B != 0 && n != 0){
			f[1] = 1;
			f[2] = 1;
			if(n > 48)
				n = n % 48;
			for(int i = 3;i <= n;i++){
				f[3] = (A * f[2] + B * f[1]) % 7;
				f[1] = f[2];
				f[2] = f[3];
			}
			if(n >= 3)
				System.out.println(f[3]);
			else
				System.out.println(1);
			A = scan.nextInt();
			B = scan.nextInt();
			n = scan.nextInt();
		}
	}
}

f[n]模7的余数在0～6，且与f[n-1]和f[n-1]模7的余数有关。f[n-1]和f[n-2]模7余数的组合不超过49种，由鸽巢原理知，f[n]的模7余数出现的周期不超过49。

上面的代码中，如果没有if(n > 48)那一行，设A=B=1，n = 48时，n = n % 48 = 0，所以输出1，而事实上f[48] = 0。

可提交的结果居然AC！看来测试数据还是有漏洞的。