Convert a Number to Any Base

/*
 * Problem : Convert a number.
 * Input   : Two integers: n and the base.
 * Output  : The digits.
 * Approach: Repeated division.
 * Time    : O(log n)
 * Space   : O(log n)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String solve(long a, long b) {
        // Step 1: A number in base b is found by repeated division. The remainders are the digits, from right to left.
        if (a == 0) {
            return "0";
        }
        String digits = "0123456789abcdefghijklmnopqrstuvwxyz";
        StringBuilder text = new StringBuilder();
        long remaining = a;

        // Step 2: The remainder after division by b is the next digit. Then divide by b.
        while (remaining > 0) {
            text.append(digits.charAt((int) (remaining % b)));
            remaining /= b;
        }

        // Step 3: The digits came out in reverse order, so we reverse them.
        return text.reverse().toString();
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        long a = scanner.nextLong();
        long b = scanner.nextLong();
        System.out.println(solve(a, b));
    }
}