Here's some pointers (no pun intended) to get you on your way:
- Every position in a Node represents one digit of the full number. Knowing this, the addition algorithm sums up 2 equal positions and takes any carry over to the next position.
- Subtracting is a bit different, what do you do different when you subtract two large numbers than when you add them, do it on a paper, then try to code it.
Please let us know where you get stuck or what part specifically you need help with if you need any further help.