Force shuffled decks to be possible to win

[Costava]

The game would be more fun if it only generated shuffled decks that are possible to win.

The getShuffledDeck method of the Solitaire class is where shuffled decks are generated. Currently, decks are randomly shuffled. It is possible to create an impossible deck.

Any necessary random number generation should come from the existing pseudorandom number generator member srng.

[thomashewett]

I'm happy to give this a crack

[Costava]

I'm happy to give this a crack

I assigned the issue to you @thomashewett 👍

[thomashewett]

Did a bit of research and it seems that this is an incredibly complex problem to solve. Currently there are four ways to implement to implement something like this.

1. Deal a deck and brute force (or hueristically) solve the puzzle before displaying to the user. If it is solvable, give to user, if not, reshuffle. Problem with this is that it is incredibly taxing at runtime and involves creating a solitaire solver. Could be helpful in giving the user hints for next move however.

2. Have a pre-prepared list of solvable deck configurations that are randomly selected from. (not a good solution)

3. work in reverse to create the deck by starting in the finished position and randomly work back to a deck. This would not give the subset of all solvable decks within the 52! possible combinations and could potentially lead to patterns to solving.

4. Ignore complete solvability and instead opt for rejecting decks that have limited number of beginning moves (e.g. x number of starting moves available with a fresh deck). This would be helpful in 3 card flip to prevent early unsolvables, but much less helpful in single card flip.

Overall, I think the complexity to solve this issue is a bit bigger than I originally thought and I'm afraid I don't think I would be of much use trying to solve this 😅. That being said, pretty much all implementations of solitaire available give the user a random deck, with a ~80% solvability rate (given perfect information), but since not all cards are shown to the player, a single wrong move can make the game unsolvable from that point onwards. So I don't think it would be much of an issue leaving the deck as truly random.

[manthan2501]

I would like to contribute on this. Kindly assign me work.

[Costava]

thomashewett has posted some valuable insight above.
@manthan2501 what is your plan for this issue?