Tower of Hanoi using Recursion in Java Example - Data structures and Algorithms by Java Examples

/*
 *
 * A (source tower), B (auxiliary tower) and C (destination tower).
 *
 * Step for n towers to move towards A to C using B. Can move one at a time. use empty tower as auxiliary tower.
 *
 * Steps:
 * 1) Move n-1 A(source) to B(destination) using C(auxiliary).
 * 2) Move nth from A(source) to C(destination).
 * 3) Move n-1 B(source) to C(destination) using A(auxiliary).
 
 * If A has 1 rod then move A(source) to C(destination) directly.
 */
 
class TowersOfHanoiPuzzle {
    public static void TOH(int n,int A, int B, int C) {
        if (n == 1) {
            System.out.println("("+A+","+C+")");
            return;
        }
          
        //Move n-1 A(source) to B(destination) using C(auxiliary).
        TOH(n-1,A,C,B);
          
        //Move nth from A(source) to C(destination).
        System.out.println("("+A+","+C+")");
          
        //Move n-1 B(source) to C(destination) using A(auxiliary).
        TOH(n-1,B,A,C);
    }
      
    public static void main(String[] args) {
         
        //Calling TOH method with 4 rods in three towers (1,2,3).
        TOH(4,1,2,3);
    }
}