HDU 1005 Number Sequence

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

int main()
{

freopen("C:\\CODE\\in.txt", "r", stdin);
//freopen("C:\\CODE\\out.txt","w",stdout);

int A,B,n;
int a[100]={0};
a[0]=0;a[1]=a[2]=1;
while(~scanf("%d%d%d",&A,&B,&n)) {
if(A+B+n == 0)
break;
int i;
for(i=3;i<100;i++){
a[i]=(A*a[i-1]+B*a[i-2])%7;
if(a[i]==a[i-1] && a[i]==1)
break;
}
i=i-2;
n=n%i;
if(n == 0) n=i; //若没有这句，会错误
printf("%d\n",a
);

}

fclose(stdin);
return 0;
}