class Euler{

    public static void main(String[] args){

        int currentA = 100;
        int currentB = 100;
        int product = 0;
        int finalProduct = 0;

        //loops through currentA and currentB for values 100-999. I wanted to use currentA and currentB in the for loops, but I got a "duplicate local variable" exception
        for(int currentA1 = 100; currentA1 <= 999; currentA1++){
            for(int currentB1 = 100; currentB1 <= 999; currentB1++){

                //Calculates the product, passes the product to inPalindrome, and records the largest palindrome product
                product = currentA * currentB;
                if(isPalindrome(product) && product > finalProduct){
                        finalProduct = product;
                }
                currentB++;
            }
            currentA++;
        }
        //Prints the final answer.
        System.out.printf("The answer is %d.", finalProduct);
    }

    //Checks if an integer is a palindrome
    public static boolean isPalindrome(int candidate){

        int hunThous = 0;
        int tenThous = 0;
        int thous = 0;
        int huns = 0;
        int tens = 0;
        int ones = 0;
        int which = 0;

        //Sets variables equal to individual digits for 5-digit numbers.
        if(candidate >= 10_000 && candidate <= 99_999){
            tenThous = candidate / 10000;
            thous = candidate % 10000 / 1000;
            huns = candidate % 1000 / 100;
            tens = candidate % 100 / 10;
            ones = candidate % 10;

            which = 1;

        //Sets variables equal to individual digits for 6-digit numbers.
        }else if(candidate >= 100_000 && candidate <= 999_999){
            hunThous = candidate / 100_000;
            tenThous = candidate % 100_000 / 10000;
            thous = candidate % 10000 / 1000;
            huns = candidate % 1000 / 100;
            tens = candidate % 100 / 10;
            ones = candidate % 10;

            which = 2;


        }else{
            System.out.println("Error. Product not within range: 10,000 - 999,999.");
        }

        //Checks to see if opposite digits match. Palindromes will have matching opposite digits.
        if(which == 1 && tenThous == ones && thous == tens){
            return true;
        }else if(which == 2 && hunThous == ones && tenThous == tens && thous == huns){
            return true;
        }else{
            return false;
        }
        }
    }