HDUACM 1005

http://acm.hdu.edu.cn/showproblem.php?pid=1005

#include <cstring>#include <cstdio>#include <cstdlib>#include<iostream>using namespace std; int rec[51]; int main(){     int a, b, n;     rec[0] = rec[1] = rec[2] = 1;     while(cin>>a>>b>>n&&(a!=0||b!=0||n!=0))     {         int beg, end, flag = 0;         for( int i = 3; i <= n && !flag; ++i )         {             rec[i] = ( a * rec[i-1] + b * rec[i-2] ) % 7;             for( int j = 2; j <= i - 1; ++j )             {               if( rec[i] == rec[j] && rec[i-1] == rec[j-1] )               {                     beg = j, end = i;                     flag = 1;                     break;               }           }        }         if( flag )         {             cout<<rec[beg+(n-end)%(end-beg)]<<endl;         }         else             cout<<rec[n]<<endl;     }     return 0;}