package net.nereson.euler.problem04;

import net.nereson.euler.StopWatch;

/**
 * <h1>Problem 04</h1>
 *
 * <p>A palindromic number reads the same both ways. The largest palindrome made from
 * the product of two 2-digit numbers is 9009 = 91 × 99.</p>
 *
 * <p>Find the largest palindrome made from the product of two 3-digit numbers.</p>
 *
 * @author <a href="mailto:@gmail.com">mnereson</a>
 * @see <a href="http://projecteuler.net/index.php?section=view&id=20">Euler; Problem 20</a>
 */
public class Problem04 {

    public void run() {

        final int MAX_VALUE = 999;
        final int MIN_VALUE = 100;

        int a = MAX_VALUE;
        int b = MAX_VALUE;

        int test = 0;
        int keeper = 0;

        int keeperA = 0;
        int keeperB = 0;

        while (a >= MIN_VALUE) {

            while (b >= MIN_VALUE) {

                test = a * b;

                if (isPalindrome(test))
                    if (test > keeper) {
                        keeper = test;
                        keeperA = a;
                        keeperB = b;
                    }

                b--;
            }

            a--;
            b = MAX_VALUE;
        }

        System.out.print(keeperA + " * " + keeperB + " = ");
        System.out.println(keeper);
    }

    public boolean isPalindrome(int number) {

        String word = String.valueOf(number);

        int left = 0;
        int right = word.length() - 1;

        while (left < right) {

            if (word.charAt(left) != word.charAt(right))
                return false;

            left++;
            right--;
        }

        return true;
    }

    public static void main(String[] args) {

        StopWatch stopWatch = new StopWatch("Problem04");

        Problem04 problem04 = new Problem04();
        problem04.run();

        System.out.println(stopWatch.getTimeString());
    }

}