password cracker solution

gistfile1.java

import java.util.ArrayList;
import java.util.List;


public class PasswordGen {
  
	public static void main(String[] args) {
		List<Character> cs = new ArrayList<Character>();
		cs.add('a');
		cs.add('b');
		cs.add('c');
		cs.add('d');
		
		PasswordGen pw = new PasswordGen(cs,10);
		String test = findpass(pw,"");
		System.out.printf("pass is %s\n",test);
		pw.CHEAT();
	}
	
	static String findpass(PasswordGen p, String cur) {
		if (cur.length() > p.get_maxlen()) {
			return null;
		} else if (p.is_correct(cur)) {
			return cur;
		} else {
			String search = null;
			for (char c : p.get_charset()) {
				String val = findpass(p,cur+c);
				if (val != null) {
					search = val;
				}
			}
			return search;
		}
	}
	
	
	private String pass;
	private int maxlen;
	private List<Character> charset;
	
	public PasswordGen(List<Character> charset, int maxlen) {
		this.charset = charset;
		this.maxlen = maxlen;
		int tarlen = (int) (Math.random()*this.maxlen)+1;
		StringBuilder b = new StringBuilder();
		for(int i = 0; i < tarlen; i++) {
			b.append(this.charset.get((int) (this.charset.size()*Math.random())));
		}
		this.pass = b.toString();
	}
	
	public int get_maxlen() {
		return this.maxlen;
	}
	
	public boolean is_correct(String tar) {
		return pass.equals(tar);
	}
	
	public List<Character> get_charset() {
		return this.charset;
	}
	
	public void CHEAT() {
		System.out.printf("CHEAT:'%s', maxlen:%d charset:%s\n", this.pass,this.charset.size(),this.charset.toString());
	}

}