Project Euler Problem 4

Problem 4

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 99.

Find the largest palindrome made from the product of two 3-digit numbers.

The solution is to multiply each three digit number and check if its a palindrome or not.

public class ProblemFour {
    public static void main(String[] args) {
        int palindrome = 9009;

        for (int i = 999; i > 99; --i) {
            for (int j = i; j > 99; --j) {
                int product = i * j;

                if (isPalindrome(String.valueOf(product)) &&
                        (product > palindrome)) {
                    palindrome = product;
                }
            }
        }

        System.out.println(palindrome);
    }

    public static boolean isPalindrome(String data) {
        char[] array = data.toCharArray();
        int reverseIndex = array.length - 1;
        int index = 0;

        while (index < reverseIndex) {
            if (array[index] != array[reverseIndex]) {
                return false;
            }

            ++index;
            --reverseIndex;
        }

        return true;
    }
}