hdu 1005 Number Sequence

 

AC code:

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