Palindrome Number

/*
 * Problem : Check if a number is a palindrome.
 * Input   : One integer.
 * Output  : true or false.
 * Approach: Reverse the digits and compare with the original.
 * Time    : O(d)
 * Space   : O(1)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method receives a number and returns true if the number is a palindrome.
    static boolean isPalindrome(long number) {
        // Step 1: A negative number is not a palindrome because of the minus sign.
        if (number < 0) {
            return false;
        }

        // Step 2: Save the original number. We change "remaining" in the loop.
        long remaining = number;

        // Step 3: Build the reversed number. It starts at 0.
        long reversed = 0;

        // Step 4: Repeat until no digits are left.
        while (remaining > 0) {
            // Step 4a: Add the last digit to the end of the reversed number. Example: 12 -> 12 * 10 + 1 = 121.
            reversed = reversed * 10 + remaining % 10;

            // Step 4b: Remove the last digit. Example: 121 / 10 = 12.
            remaining = remaining / 10;
        }

        // Step 5: A palindrome is equal to its reverse.
        return reversed == number;
    }

    public static void main(String[] args) {
        long number = new Scanner(System.in).nextLong();
        System.out.println(isPalindrome(number));
    }
}