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.
3.1. vogella Java example code
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