Logic Masters Deutschland e.V.

Rules:

Normal Sudoku rules apply.

There are four trees drawn in this grid. Digits cannot repeat on a tree. Each cosmetic cage, read clockwise, is the Prüfer encoding of the tree next to it (of the same color).

In other words:
- the cells of the tree which have only one neighbour (in that tree) are called leaves, and their only neighbour is called their father
- in the first cell of the cage, write the digit of the father of the leaf with the smallest digit among leaves
- then "remove" that leaf from the tree, and again in the second cell of the cage, write the digit of the father of the leaf with the smallest digit among leaves (in the new tree)
- continue until the tree has only 2 cells (this is why the cages are size N-2 for trees of size N)

Play in Sudokupad

Example here, also available on Sudokupad

Hope you enjoy it !
Might want to grab a pen and paper