Project Euler: #8
java
Solution
You are performing integer arithmetic when you are multiplying all those characters' numeric values together. With high digits, and 13 of them, it is likely that such a product would overflow an `int`, whose max value is about 2 billion (10 digits).
The `Character.getNumericValue` method returns an `int`. Cast the first return value as a `long` to force `long` math.
long sum = (long) Character.getNumericValue(num.charAt(i))*
Character.getNumericValue(num.charAt(i+1))*
...
Incidentally, even though you have `greatestProduct` already, for some reason you defined this variable as `sum`. Just for semantics' sake, I would name it `product`.
Problem
When trying to answer this problem: The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832. 73167176531330624919225119674426574742355349194934 96983520312774506326239578318016984801869478851843 85861560789112949495459501737958331952853208805511 12540698747158523863050715693290963295227443043557 66896648950445244523161731856403098711121722383113 62229893423380308135336276614282806444486645238749 30358907296290491560440772390713810515859307960866 70172427121883998797908792274921901699720888093776 65727333001053367881220235421809751254540594752243 52584907711670556013604839586446706324415722155397 53697817977846174064955149290862569321978468622482 83972241375657056057490261407972968652414535100474 82166370484403199890008895243450658541227588666881 16427171479924442928230863465674813919123162824586 17866458359124566529476545682848912883142607690042 24219022671055626321111109370544217506941658960408 07198403850962455444362981230987879927244284909188 84580156166097919133875499200524063689912560717606 05886116467109405077541002256983155200055935729725 71636269561882670428252483600823257530420752963450 Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product? I get 2091059712 however Euler says the answer is incorrect is there anything I may be doing incorrectly? ``` public class LargestProductThirteen{ public static void main( String[] args ) { final String num = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"; long greatestProduct = 0; for (int i = 0; i < num.length() - 12; i++) { long sum = Character.getNumericValue(num.charAt(i))* Character.getNumericValue(num.charAt(i+1))* Character.getNumericValue(num.charAt(i+2))* Character.getNumericValue(num.charAt(i+3))* Character.getNumericValue(num.charAt(i+4))* Character.getNumericValue(num.charAt(i+5))* Character.getNumericValue(num.charAt(i+6))* Character.getNumericValue(num.charAt(i+7))* Character.getNumericValue(num.charAt(i+8))* Character.getNumericValue(num.charAt(i+9))* Character.getNumericValue(num.charAt(i+10))* Character.getNumericValue(num.charAt(i+11))* Character.getNumericValue(num.charAt(i+12)); if (sum > greatestProduct) greatestProduct = sum; } System.out.println(greatestProduct); } } ```