Tiles are supposed to be free when there is a side free
No.
According to wikipedia[1]: "A tile is said to be open or exposed if it can be moved either left or right without disturbing other tiles.". Also look at the photo in the wikipedia article[2]. This implementation looks correct to me.
A "free side" means being exposed on the left or right, matching your Wikipedia quote. On the other hand, OP's implementation checks if it can be moved up or down.
Comments
No.
According to wikipedia[1]: "A tile is said to be open or exposed if it can be moved either left or right without disturbing other tiles.". Also look at the photo in the wikipedia article[2]. This implementation looks correct to me.
[1]: https://en.wikipedia.org/wiki/Mahjong_solitaire
[2]: https://en.wikipedia.org/wiki/Mahjong_solitaire#/media/File:...
A "free side" means being exposed on the left or right, matching your Wikipedia quote. On the other hand, OP's implementation checks if it can be moved up or down.
Look at the shape of the puzzle and compare with the wikipedia photo. The sides logic is correct.
Although looks like the images on the tiles were indeed rotated, as mentioned in another comment[1].
[1]: https://news.ycombinator.com/item?id=47115499