ZOJ Problem Set - 2105
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
Author: CHEN, Shunbao
Source: Zhejiang Provincial Programming Contest 2004
#include < iostream >
using namespace std;
int main()
{
int a,b,d;
long n;
int arry[ 49 ];
arry[ 1 ] = 1 ;
arry[ 2 ] = 1 ;
cin >> a >> b >> n;
while (a != 0 && b != 0 && n != 0 )
{
for (d = 3 ;d <= 48 ;d ++ )
arry[d] = (arry[d - 1 ] * a % 7 + arry[d - 2 ] * b % 7 ) % 7 ;
cout << arry[(n - 1 ) % 48 + 1 ] << endl;
cin >> a >> b >> n;
}
}