# auto generate mahjong level with at least 1 way to win

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Hello everybody, Im new in game programing.

I decided to make a game like mahjong but simpler than it !

there are n tiles marked with char A-Z, they are arranged into many layer of pyramid shape . The bottom layer will have mxm tiles , the top layer will have 2x2 tiles . Here is the sample :

Game rule : User will pick 2 tiles, if they have same char then remove both . User win the game when all tiles are removed.

The problem is : How to auto generate the level randomly with at least 1 way to win . Please help , im stuck with this problem ! Thank a lot guy !

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There are several different Mah-Jongg rules out there.  It is a multi-person game much like Rummy and similar card game variants.

If you just mean the solitaire matching game (which is not Mah-Jongg but sometimes called that) then you can build up a layout in reverse.  Start by placing a pair of tiles, then place another pair of tiles, then another, then another, until all the tiles are placed. It is guaranteed winnable since you can exactly reverse the order. Just be careful to build in a somewhat regular manner to avoid adjacent tiles that you cannot place.

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There are several different Mah-Jongg rules out there.  It is a multi-person game much like Rummy and similar card game variants.

If you just mean the solitaire matching game (which is not Mah-Jongg but sometimes called that) then you can build up a layout in reverse.  Start by placing a pair of tiles, then place another pair of tiles, then another, then another, until all the tiles are placed. It is guaranteed winnable since you can exactly reverse the order. Just be careful to build in a somewhat regular manner to avoid adjacent tiles that you cannot place.

Thank for your help ! But can you give me the sample of placing those tiles because there are many layer for botton to top that make a pyramidal form ? Do i have to start placing those tiles at the top layer or the bottom layer or random layer(each tile at different layer) ?

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But can you give me the sample of placing those tiles because there are many layer for botton to top that make a pyramidal form ? Do i have to start placing those tiles at the top layer or the bottom layer or random layer(each tile at different layer) ?

I don't have an algorithm, but I could invent a likely one pretty easily.

Start with an empty board. Select a desired layout. Pick two valid tile locations (note that mid-air is probably not a valid tile location at this point). Place a tile in each. Repeat until layout is complete.

The space picking algorithm will need to follow the reverse rules of playing the game. If you can only take from endpoints or the highest level, then you can only place from where they could be taken. You would want to statistically prefer to place on short rows and bias against nearly full rows, otherwise you may get trapped in a position where you only have two adjacent positions on a single row.  If your layout rules allow odd patterns and holes, you will need to account for that in your space picking algorithm.

Worst case is you get stuck and try again with a new random seed, potentially taking a few seconds in a bad situation where many board combinations are tried and rejected.

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You'll be starting with a blank play-field, so you'll be building the layers from the bottom upwards by adding pairs of tiles to any valid and available spaces until the board is complete and ready to play.

Because tiles in upper layers are placed on top of tiles in lower layers, obviously you can't place tiles into a second (or third, fourth, etc.) layer until the layer beneath them has enough tiles.

Looking at your example image above, consider that you could not place the bottom-right tile in the second layer until all four tiles that it overlaps have already been placed.

//EDIT: Beaten to it by frob -- but hopefully between the two of us you'll have an idea of how to approach this.

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Thank for helping me so far , I will try your methods !

By the way, I found this algorithm :

http://www.formauri.es/personal/pgimeno/mj/mjsol.html

but i can't understand this algorithm , can you guys help me explain this . Thank a lot guys !

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By the way, I found this algorithm :
http://www.formauri.es/personal/pgimeno/mj/mjsol.html
but i can't understand this algorithm , can you guys help me explain this . Thank a lot guys !

Were you aware that the linked page describes an approach for solving existing puzzles rather than for generating puzzles?  We can still help you to understand it if you wish though!

Did you understand any of the explanation, or is there a specific point at which you got stuck?  Are you having trouble with some of the terminology, or do you understand all of that but are stuck on the logic of how the algorithm works?

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Were you aware that the linked page describes an approach for solving existing puzzles rather than for generating puzzles?  We can still help you to understand it if you wish though!

If the algorithm to solve an arbitrary puzzle is sufficiently constructive, it is often not hard to reverse it to produce an algorithm to generate a solvable puzzle  (though such an algorithm can probably more readily be obtained by simply reversing the game rules, as frob suggests).