Project Euler 4 - Largest palindrome product
I submitted a solution to Project Euler 4 exercise: Largest palindrome product in Java. The content of following exercise:
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 ×ばつ 99.
Find the largest palindrome made from the product of two 3-digit numbers.
I wrote a method called isPalindrome that checks is reversing of string the same as output string. I have to obviously convert int to String to check is given number is palindrome. I created palindromes list and I loop for all possible three-digits numbers that would be multiplied and I check are these products palindromes. If yes, then I add it product to list. Next, I select only maximum palindrome from list and I print it to console.
Main.java:
package pl.hubot.projecteuler.problem4;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<Integer> palindromes = new ArrayList<>();
for (int i = 100; i <= 999; i++) {
for (int j = 100; j <= 999; j++) {
if (isPalindrome(Integer.toString(i * j)))
palindromes.add(i * j);
}
}
System.out.print(Collections.max(palindromes));
}
private static boolean isPalindrome(String str) {
return str.equals(new StringBuilder(str).reverse().toString());
}
}