problem9.cpp

#include "iostream"
#include "fstream"

inline unsigned int myatoi(const char digit)
{
   switch(digit)
   {
   case '0': return 0;
   case '1': return 1;
   case '2': return 2;
   case '3': return 3;
   case '4': return 4;
   case '5': return 5;
   case '6': return 6;
   case '7': return 7;
   case '8': return 8;
   case '9': return 9;
   }
}

unsigned int mult(const char* digits)
{
   return (myatoi(digits[0]) * myatoi(digits[1])  * myatoi(digits[2]) *
         myatoi(digits[3]) * myatoi(digits[4]));
}

int main(int argc, char** argv)
{
   unsigned int max_mult = 0;
   unsigned int i = 0;
   char* digits = new char[6];

   std::fstream file;
   file.open("./number.txt");
   if(file.is_open())
   {
      while(i < 1000)
      {
         file.seekp(i);
	 //std::cout<<digits<<std::endl;
         file.get(digits, 6, '\n');
         max_mult = std::max(max_mult, mult(digits));
         ++i;
      }
   }

   file.close();
   delete[] digits;

   std::cout << max_mult<<std::endl;;
   return 0;
}