008.cpp

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#include <iostream>
using namespace std;

const int length = 1000;        //number of digits
char str[length + 1] =
  "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
//string representation of the number

inline char
no (char *p)
{
  return (*p) - '0';
}                               //change string to number

int
main ()
{
  char *p = str;                //pointer
  unsigned product =
    no (p) * no (p + 1) * no (p + 2) * no (p + 3) * no (p + 4);

  unsigned max_product = product;
  int position = 0;             //position

  do
    {
      p++;                      //move on to next digit.
      product = no (p) * no (p + 1) * no (p + 2) * no (p + 3) * no (p + 4);

      if (product > max_product)
        {
          position = p - str + 1;
          max_product = product;
        }

    }
  while (*(p + 5) != 0);        //until end of line.

  cout << "The max product is " << max_product << " at " << position <<
    "-th digit" << endl;
  return 0;
}