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Largest product of digits in a number

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This code finds the largest product of 5 consecutive digits within a given number

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  1. #include <iostream>
  2. #include <deque>
  3. #include <sstream>
  4. #include <string>
  5.  
  6. #include <boost/lexical_cast.hpp>
  7.  
  8. int main()
  9. {
  10. 	std::deque<int> digits;
  11. 	std::string number = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450";
  12. 	char* digit = new char[number.size() + 1];
  13. 	std::strcpy(digit, number.c_str());
  14. 	while (digits.size() != 5)
  15. 	{
  16. 		digits.push_back(boost::lexical_cast<int>(*digit));
  17. 		++digit;
  18. 	}
  19. 	unsigned int bestProduct = 1;
  20. 	while (*digit != '\0')
  21. 	{
  22. 		unsigned int product = digits[0] * digits[1] * digits[2] * digits[3] * digits[4];
  23. 		if (product > bestProduct)
  24. 			bestProduct = product;
  25.  
  26. 		digits.pop_front();
  27. 		digits.push_back(boost::lexical_cast<int>(*digit));
  28. 		++digit;
  29. 	}
  30.  
  31. 	std::cout << bestProduct << std::endl;
  32. 	system("pause");
  33. }

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