How do I generate a smart path without issues?

So what exactly do you need - to detect if a randomly generated board has a valid path, or to ensure that randomly generated board will always contain a valid path?

In the latter case, you can create the valid path in advance, and then every 2 seconds reveal one box of this path, plus 0-4 random boxes.

Ok let's forget for now the 2 seconds.

Imagine "on start of layout" to create 10 boxes from bottom to top.

So what i need is to give me a correct path.

Something like:

ABCDE

A____

AB___

_BC_E

A_C_E

__C__

__C__

_BCD_

AB__E

A__D_

This is a correct path. I hope make sense now! :)

Sorry, but I still don't understand -

A) Do you need to create a correct path? I.e. you need to generate a level which should definitely have a correct path from bottom to top.

or

B) Do you need to generate a random level, and then check if it contains a correct path?

.

If "A", then I would do something like this:

Basically it's to generate a random level but even your A) it's a good help. I will give a try. By the way, thanks again! :)