Problem #8

Find the greatest product of five consecutive digits in the 1000-digit number.

Nästan för enkel:

#include <iostream>

char nums[] = {
  "73167176531330624919225119674426574742355349194934"
  "96983520312774506326239578318016984801869478851843"
  "85861560789112949495459501737958331952853208805511"
  "12540698747158523863050715693290963295227443043557"
  "66896648950445244523161731856403098711121722383113"
  "62229893423380308135336276614282806444486645238749"
  "30358907296290491560440772390713810515859307960866"
  "70172427121883998797908792274921901699720888093776"
  "65727333001053367881220235421809751254540594752243"
  "52584907711670556013604839586446706324415722155397"
  "53697817977846174064955149290862569321978468622482"
  "83972241375657056057490261407972968652414535100474"
  "82166370484403199890008895243450658541227588666881"
  "16427171479924442928230863465674813919123162824586"
  "17866458359124566529476545682848912883142607690042"
  "24219022671055626321111109370544217506941658960408"
  "07198403850962455444362981230987879927244284909188"
  "84580156166097919133875499200524063689912560717606"
  "05886116467109405077541002256983155200055935729725"
  "71636269561882670428252483600823257530420752963450"
};

int main(int argc, char *argv[])
{
  for (size_t i = 0; i < sizeof(nums); ++i)
    nums[i] -= '0'; // Just convenience

  int largest_product = 0;
  for (size_t i = 0; i < sizeof(nums) - 5; ++i)
  {
    int p = nums[i]*nums[i+1]*nums[i+2]*nums[i+3]*nums[i+4];
    largest_product = std::max(p, largest_product);
  }

  std::cout << "Answer is " << largest_product << std::endl;
  return 0;
}