Home Tutorials Training Consulting Products Books Company Donate Contact us


Get more...

Training Events

Towers of Hanoi in Java. This article describes how to solve the Towers of Hanoi in Java.

1. Towers of Hanoi

The towers of hanoi is a popular problem. You have three poles and n disks which fit on the poles. All disks have different sizes. They are stacked on pole 1 in the order of their sizes. The largest disk is on the bottom, the smallest is on the top.

The task is to move all disk from pole 1 to pole 3 under the following restrictions.

  • Only one disk can be moved.

  • A larger disk can not be placed on a smaller disk.

The recursive algorithm works like the following: move n-1 disk from the starting pole to the pole which is neither start nor target (intermediate), move disk n to the target pole and then move n-1 disk from the intermediate pole to the target pole. The n-1 disks are moved recursively.

2. Implementation in Java

Create a Java project "de.vogella.algorithms.towersofhanoi".

Create the following program.

package de.vogella.algorithms.towersofhanoi;

/**
 * Towers of Hanoi
 * Pole are labeled 1, 2,3
 * Each disk is also labeled
 * @author Lars Vogel
 *
 */
public class TowersOfHanoi {
    public static void move(int n, int startPole, int endPole) {
        if (n== 0){
            return;
        }
        int intermediatePole = 6 - startPole - endPole;
        move(n-1, startPole, intermediatePole);
        System.out.println("Move " +n + " from " + startPole + " to " +endPole);
        move(n-1, intermediatePole, endPole);
    }

    public static void main(String[] args) {
        move(5, 1, 3);
    }


}

3. Links and Literature

Nothing listed.

If you need more assistance we offer Online Training and Onsite training as well as consulting

Legal Privacy Policy Change consent