Logic Masters Deutschland e.V.

Dutch Flat Mates Series
The Dutch Flat Mates series has been a weekly series since 18 October 2023. It was initiated by Flinty and many guest authors have written variants for the series. Here is a spreadsheet link for all the previous puzzles, which also has a few teasers for the last remaining upcoming constraints. And here you find all episodes in this puzzle portal.
More than a year ago I had already contact with Flinty about my contribution to the series, so I am glad I finally made it just in time. :)

Dutch Flat Mates
Apply classis sudoku rules.
Every digit 5 has either a 1 directly above it, or a 9 directly below it, or both.

Next to N
Clues on the left and above the grid indicate all direct neighbours of the digit N in the corresponding row or column, where N is the index number of the row or column. Clues are placed in ascending order, and not necessarily the order in which they appear in the solved grid. Question marks may be replaced by any digit 1-9. The index numbers of the rows and columns are given in a grey font below and on the right of the grid for your convenience.

Solve online in SudokuPad