HDU - Number Sequence

Number Sequence

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 75278    Accepted Submission(s): 17496

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

#include <stdio.h>

int main()
{
	int a,b,n,ans[50];
	while(scanf("%d%d%d",&a,&b,&n),a+b+n)
	{
		ans[0] = ans[1] = 1;
		for(int i = 2; i < 49; i++)
		{
			ans[i] = (a*ans[i-1] + b*ans[i-2]) % 7;
		}
		printf("%d\n",ans[(n-1)%49]);
	}
	return 0;
}