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Java Program for Tower of Hanoi

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Tower of Hanoi is a mathematical puzzle where we have three rods and n disks. The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules: 1) Only one disk can be moved at a time. 2) Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack. 3) No disk may be placed on top of a smaller disk. faq.disk3

Java




// Java recursive program to solve tower of hanoi puzzle
 
class GFG
{
    // Java recursive function to solve tower of hanoi puzzle
    static void towerOfHanoi(int n, char from_rod, char to_rod, char aux_rod)
    {
        if (n == 1)
        {
            System.out.println("Move disk 1 from rod " +  from_rod + " to rod " + to_rod);
            return;
        }
        towerOfHanoi(n-1, from_rod, aux_rod, to_rod);
        System.out.println("Move disk " + n + " from rod " +  from_rod + " to rod " + to_rod);
        towerOfHanoi(n-1, aux_rod, to_rod, from_rod);
    }
     
    //  Driver method
    public static void main(String args[])
    {
        int n = 4; // Number of disks
        towerOfHanoi(n, \'A\', \'C\', \'B\');  // A, B and C are names of rods
    }
}


Output:

 Move disk 1 from rod A to rod B
 Move disk 2 from rod A to rod C
 Move disk 1 from rod B to rod C
 Move disk 3 from rod A to rod B
 Move disk 1 from rod C to rod A
 Move disk 2 from rod C to rod B
 Move disk 1 from rod A to rod B
 Move disk 4 from rod A to rod C
 Move disk 1 from rod B to rod C
 Move disk 2 from rod B to rod A
 Move disk 1 from rod C to rod A
 Move disk 3 from rod B to rod C
 Move disk 1 from rod A to rod B
 Move disk 2 from rod A to rod C
 Move disk 1 from rod B to rod C

Time Complexity: O(2n)

Auxiliary Space: O(n)

Please refer complete article on Program for Tower of Hanoi for more details!


Last Updated : 16 Jun, 2022
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