HDU 1005 Number Sequence

[align=left]Problem Description[/align]
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).

[align=left]Input[/align]
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.

[align=left]Output[/align]
For each test case, print the value of f(n) on a single line.

[align=left]Sample Input[/align]

1 1 3 1 2 10 0 0 0

[align=left]Sample Output[/align]

2 5

#include<stdio.h>
int main()
{
int i, a, b, f[200]={0};
__int64 n;
while(scanf("%d%d%I64d", &a, &b, &n) && (a||b||n))
{
if (n == 1 || n == 2)
{
printf("1\n");
continue;
}
f[1]=1;
f[2]=1;
for (i=3; i<=200; i++)
{
f[i]=(f[i-1]*a+f[i-2]*b)%7;
if ((i != 3) && (f[i] == 1) && (f[i-1] == 1))
{
f[0]=f[i-2];
break;
}
}
printf("%d\n", f[n%(i-2)]);
}
return 0;
}