Java Examples - Solving Tower of Hanoi


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Problem Description

How to use method for solving Tower of Hanoi problem?

Solution

This example displays the way of using method for solving Tower of Hanoi problem( for 3 disks).

public class MainClass {
   public static void main(String[] args) {
      int nDisks = 3;
      doTowers(nDisks, 'A', 'B', 'C');
   }
   public static void doTowers(int topN, char from, char inter, char to) {
      if (topN == 1) {
         System.out.println("Disk 1 from " + from + " to " + to);
      } else {
         doTowers(topN - 1, from, to, inter);
         System.out.println("Disk " + topN + " from " + from + " to " + to);
         doTowers(topN - 1, inter, from, to);
      }
   }
}

Result

The above code sample will produce the following result.

Disk 1 from A to C
Disk 2 from A to B
Disk 1 from C to B
Disk 3 from A to C
Disk 1 from B to A
Disk 2 from B to C
Disk 1 from A to C

The following is an another sample example of Tower of Hanoi

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);
   }
}

The above code sample will produce the following result.

Move 1 from 1 to 3
Move 2 from 1 to 2
Move 1 from 3 to 2
Move 3 from 1 to 3
Move 1 from 2 to 1
Move 2 from 2 to 3
Move 1 from 1 to 3
Move 4 from 1 to 2
Move 1 from 3 to 2
Move 2 from 3 to 1
Move 1 from 2 to 1
Move 3 from 3 to 2
Move 1 from 1 to 3
Move 2 from 1 to 2
Move 1 from 3 to 2
Move 5 from 1 to 3
Move 1 from 2 to 1
Move 2 from 2 to 3
Move 1 from 1 to 3
Move 3 from 2 to 1
Move 1 from 3 to 2
Move 2 from 3 to 1
Move 1 from 2 to 1
Move 4 from 2 to 3
Move 1 from 1 to 3
Move 2 from 1 to 2
Move 1 from 3 to 2
Move 3 from 1 to 3
Move 1 from 2 to 1
Move 2 from 2 to 3
Move 1 from 1 to 3

java_methods.htm

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