具有递归回溯的动态树结构。

I have this problem that I need to solve a recursive backtracking issue. It looks a lot like the n-queen problem, but is different in the way that it uses different candidates with a a-symmetric board. There are a total of four different candidates that each have dependency's on one and another. I have 2 aces, 2 kings, 2 queens and 2 jacks. Each ace has to be next to (horizontal or vertical) to a king, each king has to be next to a queen and each queen has to be next to a jack and non of the pieces can have duplicates next to them. The board with the right solution looks like this:I have this problem that I need to solve a recu