[ CHALLENGE ] Buy a better calculator... or try to make the best use of this one

Question

Imagine you own a calculator that can only perform two operations:
1. Add one (+1), and
2. Multiply by two ( *2)
The task is to determine how many ways (different sequences of these two operations) are there to get a number starting from another number.

For example:
> start = 3, finish = 6.
There are two ways to make it, listing the numbers of operations they are [1,1,1] and [2]
> start = 3 finish = 8
Three ways: [1,1,1,1,1], [1,2], [2,1,1]

(basic) just count the number of all possible ways
(extra) list all these ways

my (basic) try using recursion is here: https://code.sololearn.com/cRWKHX9BChjF/#java

Answer 1

@MARTA
There was an update to the IOS app which added lessons in it. unfortunately, if you can't find Lesson Factory in main menu similar to Quiz Factory then it may not be available for now. They may add it in a future app update.

Answer 2

You can submit this as an assignment in lesson factory; It can even unlock you some badges and get your challenge better visibility.

https://www.sololearn.com/discuss/1082512/?ref=app

Answer 3

@ Lord Krishna: that would be great. I couldn’t actually find how I could submit it any way except q&a. I can reach SL via web / my IPhone, I thought quiz factory is only reachable from android, isn’t it?