Collatz Sequence

/*
 * Problem : Print the Collatz sequence of a number.
 * Input   : One positive integer n.
 * Output  : The sequence from n to 1 on one line, separated by a space.
 * Approach: If the number is even, halve it. If it is odd, multiply by 3 and add 1.
 * Time    : Unknown (depends on n)
 * Space   : O(length)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        long number = new Scanner(System.in).nextLong();
        StringBuilder line = new StringBuilder();

        // Step 1: Write the first number of the sequence.
        line.append(number);

        // Step 2: Repeat until the number is 1.
        while (number != 1) {
            // Step 3: If the number is even, divide it by 2. Otherwise multiply it by 3 and add 1.
            if (number % 2 == 0) {
                number = number / 2;
            } else {
                number = 3 * number + 1;
            }

            // Step 4: Write the new number after a space.
            line.append(" ").append(number);
        }

        // Step 5: Print the sequence. We use long, because the numbers can grow large before they fall to 1.
        System.out.println(line);
    }
}