Hanoi Towers 3411

package pack1;

import java.util.Arrays;
import java.util.Collection;
import java.util.Deque;
import java.util.LinkedList;
import java.util.List;

/**
 * Created by vkondratiev on 06.08.2021
 */
public class HanoiTowers {

    private static final List<String> STRINGS = Arrays.asList(
            "ALPHA", "BRAVO", "CHARLIE", "DELTA", "ECHO", "FOXTROT", "GOLF", "HOTEL", "INDIA", "JULIET", "KILO", "LIMA",
            "MIKE", "NOVEMBER", "OSCAR", "PAPA", "QUEBEC", "ROMEO", "SIERRA", "TANGO", "UNIFORM", "VICTOR", "WHISKEY",
            "X-RAY", "YANKEE", "ZULU"
    );
    private static final int SIZE = 4;
    private int steps;
    private final HanoiTower[] towers;

    public HanoiTowers() {
        towers = new HanoiTower[]{new HanoiTower("SOURCE"), new HanoiTower("BUFFER"), new HanoiTower("RESULT")};
        steps = 0;
        towers[0].fill(STRINGS.subList(0, SIZE));
    }

    public static void main(String[] args) {
        HanoiTowers hanoiTowers = new HanoiTowers();
        System.out.println("start position:\n" + hanoiTowers);

        hanoiTowers.runTask();
        System.out.println("finish position:\n" + hanoiTowers);
    }

    private void runTask() {
        towers[0].moveAll(towers[1], towers[2], towers[0].size(), this);
        System.out.printf("%nmoving %d elements ................ %d steps%n", SIZE, steps);
    }

    @Override
    public String toString() {
        if (towers.length != 3)
            throw new RuntimeException();
        return String.format("%s%n%s%n%s", towers[0].toString(), towers[1].toString(), towers[2].toString());
    }

    class HanoiTower {

        private final String name;
        private final Deque<String> content = new LinkedList<>();

        HanoiTower(String name) {
            this.name = name;
        }

        void moveElement(HanoiTower fromTower, HanoiTowers hanoiTowers) {
            String element = fromTower.content.pollLast();
            content.addLast(element);
            System.out.printf("%nmoving %s from %s to %s:%n%s%n", element, fromTower.name, this.name, hanoiTowers);
        }

        private void moveAll(HanoiTower buffer, HanoiTower result, int amount, HanoiTowers hanoiTowers) {
            if (amount == 0) {
                return;
            }
            steps++;
            amount--;
            this.moveAll(result, buffer, amount, hanoiTowers);
            result.moveElement(this, hanoiTowers);
            buffer.moveAll(this, result, amount, hanoiTowers);
        }

        void fill(Collection<String> elements) {
            content.clear();
            content.addAll(elements);
        }

        int size() {
            return content.size();
        }

        @Override
        public String toString() {
            return String.format(" %s: %s", name, content);
        }
    }
}