import java.util.ArrayDeque;
import java.util.Deque;

public class HanoiStack {
    // A job still to do: move n disks, or, when single is true, move just disk n.
    record Job(int n, char source, char target, char spare, boolean single) {}

    static void hanoi(int disks, char source, char target, char spare) {
        Deque<Job> jobs = new ArrayDeque<>();
        jobs.push(new Job(disks, source, target, spare, false));

        while (!jobs.isEmpty()) {
            Job job = jobs.pop();
            if (job.single()) {
                System.out.println("Move disk " + job.n() + " from " + job.source() + " to " + job.target());
            } else if (job.n() > 0) {
                // Pushed in reverse: a stack hands back the last thing pushed first.
                jobs.push(new Job(job.n() - 1, job.spare(), job.target(), job.source(), false));
                jobs.push(new Job(job.n(), job.source(), job.target(), job.spare(), true));
                jobs.push(new Job(job.n() - 1, job.source(), job.spare(), job.target(), false));
            }
        }
    }

    public static void main(String[] args) {
        hanoi(3, 'A', 'C', 'B');
    }
}