CODEWITHSUNDEEP
java
Cuthalion
Cuthalion

Reputation: 21

Project Euler #8 answer fails to be true

https://projecteuler.net/problem=8

I have looked in some topics about the problem but ı could not understand why my code gives me the wrong answer.When i arrange my code to give the greatest product of 4 adjacent digits it gives the true answer: 5832 as given in the question,however, in the case of finding the greatest product of 13 adjacent digits it gives the answer: 2091059712 which turned out to be wrong.

public class Euler extends IllegalArgumentException
{
    public static void main(String[] args) 
    {
        String str ="73167176531330624919225119674426574742355349194934"+
                    "96983520312774506326239578318016984801869478851843"+
                    "85861560789112949495459501737958331952853208805511"+
                    "12540698747158523863050715693290963295227443043557"+
                    "66896648950445244523161731856403098711121722383113"+
                    "62229893423380308135336276614282806444486645238749"+
                    "30358907296290491560440772390713810515859307960866"+
                    "70172427121883998797908792274921901699720888093776"+
                    "65727333001053367881220235421809751254540594752243"+
                    "52584907711670556013604839586446706324415722155397"+
                    "53697817977846174064955149290862569321978468622482"+
                    "83972241375657056057490261407972968652414535100474"+
                    "82166370484403199890008895243450658541227588666881"+
                    "16427171479924442928230863465674813919123162824586"+
                    "17866458359124566529476545682848912883142607690042"+
                    "24219022671055626321111109370544217506941658960408"+
                    "07198403850962455444362981230987879927244284909188"+
                    "84580156166097919133875499200524063689912560717606"+
                    "05886116467109405077541002256983155200055935729725"+
                    "71636269561882670428252483600823257530420752963450";
        int max=0;
        int product=1;

        for(int a=0;a<str.length()-12;a++)
        {
            product=1;
            for(int i=a;i<a+13;i++)
            {
                product*=Integer.parseInt(str.substring(i,i+1));
            }
            if(product>max)
                max=product;
        }
        System.out.println(max);                
    }
}

Upvotes: 0

Views: 230

Answers (2)

2016rshah
2016rshah

Reputation: 681

This Project Euler problem has an answer that causes the int you are storing your answer in to overflow. Instead you need to use a long to store your answer that takes more memory but won't overflow as quickly or a BigInteger which has arbitrary precision.

To fix your code in the most simple way possible change the initialization of the variables to this:

long max=0;
long product=1;

Links that might help:

Upvotes: 2

Tolis Stefanidis
Tolis Stefanidis

Reputation: 31

Change max and product to long. int is too small to hold the product :)

Upvotes: 0

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