hdu1005 Number Sequence

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 31 2 100 0 0

 

Sample Output

25

 

Author

CHEN, Shunbao

 

Source

ZJCPC2004

#include<stdio.h>int main(){    int a,b,n;    while(scanf("%d%d%d",&a,&b,&n)!=EOF)    {        if(a==0&&a==b&&b==n)            break;        int i,ans[50];        ans[1]=ans[2]=1;        n=n%49;        for(i=3; i<=n; i++)        {            ans[i]=((a*ans[i-1])+(b*ans[i-2]))%7;        }        printf("%d\n",ans[n]);    }    return 0;}

7*7=49