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Java

Diego Murray
Diego Murray
2,515 Points
Posted by Diego Murray
Diego Murray
2,515 Points

Euler Problem 8 - Bug

Find the 13 consecutive digits in this 1000 digit number that have the largest product.

public class Main {

    static final String BIGNUM = "73167176531330624919225119674426574742355349194934" +
            "96983520312774506326239578318016984801869478851843" +
            "85861560789112949495459501737958331952853208805511" +
            "12540698747158523863050715693290963295227443043557" +
            "66896648950445244523161731856403098711121722383113" +
            "62229893423380308135336276614282806444486645238749" +
            "30358907296290491560440772390713810515859307960866" +
            "70172427121883998797908792274921901699720888093776" +
            "65727333001053367881220235421809751254540594752243" +
            "52584907711670556013604839586446706324415722155397" +
            "53697817977846174064955149290862569321978468622482" +
            "83972241375657056057490261407972968652414535100474" +
            "82166370484403199890008895243450658541227588666881" +
            "16427171479924442928230863465674813919123162824586" +
            "17866458359124566529476545682848912883142607690042" +
            "24219022671055626321111109370544217506941658960408" +
            "07198403850962455444362981230987879927244284909188" +
            "84580156166097919133875499200524063689912560717606" +
            "05886116467109405077541002256983155200055935729725" +
            "71636269561882670428252483600823257530420752963450";

    static final int DIGITS = 13;

    public static void main(String[] args) {
        System.out.println("The greatest product is: " + getMaxProduct());
    }

    public static long getMaxProduct(){
        long largestProduct = 0; 

        for (int i = 0; i < BIGNUM.length() - DIGITS; i++) {
            long prod = 1;

            for(int j = 0; j < DIGITS; j++) {
                prod *= BIGNUM.charAt(i); // I think this line is the problem..
            }
            largestProduct = Math.max(prod, largestProduct);
        }
        return largestProduct;
    }
}

1 Answer

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

demo:

class Main {
  public static void main(String[] args) {

    String x = "5334456678231";
    long prod = 1 * x.charAt(5); // I think this line is the problem..
    System.out.println(prod); 
  }
}

The output is 53. While char values are numeric, their values don't correlate to their real values.

Simon Coates
Simon Coates
28,694 Points
Simon Coates
Simon Coates
28,694 Points

but they are in sequence, so you can use a displacement to get their numeric values. something like (BIGNUM.charAt(4)-48)