Disclaimer: It's highly recommend trying to solve it before looking at the solution.

Approach

Algorithm

This problem can be solved using recursion.
Recursion problems consist of the base cases, recursion calls where we don't have to worry about the result and small a calculation. While making recursion calls we just have to assume that we will get the result.
On the first recursion, call move n-1 disks from source rod to auxiliary using destination rod. This is a recursion call that goes till n becomes zero. We just have to assume that this will put n-1 disks into the auxiliary rod.
Here we will do some small calculations that are put the remaining disk from the source rod to the destination rod since we are left with only one disk.
Now make a recursion call that will move n-1 disks from auxiliary rod to destination rod using source rod.
In the base case when n becomes zero we will simply return.

Code