import java.util.Arrays;

public class BruteForce {

    public static void main(String[] args) {
        String password = "pass";
        char[] charset = "abcdefghijklmnopqrstuvwxyz".toCharArray();
        BruteForce bf = new BruteForce(charset, 1);

        String attempt = bf.toString();
        while (true) {
            if (attempt.equals(password)) {
                System.out.println("Password Found: " + attempt);
                break;
            }
            attempt = bf.toString();
            System.out.println("Tried: " + attempt);
            bf.increment();
        }
    }

    private char[] cs; // Character Set
    private char[] cg; // Current Guess

    public BruteForce(char[] characterSet, int guessLength) {
        cs = characterSet;
        cg = new char[guessLength];
        Arrays.fill(cg, cs[0]);
    }

    public void increment() {
        int index = cg.length - 1;
        while (index >= 0) {
            if (cg[index] == cs[cs.length - 1]) {
                if (index == 0) {
                    cg = new char[cg.length + 1];
                    Arrays.fill(cg, cs[0]);
                    break;
                } else {
                    cg[index] = cs[0];
                    index--;
                }
            } else {
                cg[index] = cs[Arrays.binarySearch(cs, cg[index]) + 1];
                break;
            }
        }
    }

    public String toString() {
        return String.valueOf(cg);
    }
}