Logic Masters Deutschland e.V.

This puzzle is inspired by Calesch's Friendlynori, one of my favorite puzzles.

• Chaos Construction: Divide the grid into regions of 9 orthogonally connected cells each, such that every cell is part of exactly one region. Place the digits 1-9 exactly once in each row, column and region. A region border is given.
• Norinori: Shade some cells so that each shaded cell is orthogonally adjacent to exactly 1 other shaded cell (i.e. shaded cells form 1x2 dominoes which do not touch orthogonally). Each region must contain exactly 2 shaded cells (which may or may not be in the same domino).
• Each shaded cell must be 'friendly', meaning its digit matches its row or column number (numbered 1-9 top to bottom/left to right). Each region must have at least one shaded cell acts like a cave clue (i.e. it indicates the number of cells seen in every orthogonal directions combined, including itself, only region borders obstruct vision).
• Arrows: cell contains arrow(s) may not be shaded. Either there are exactly two dominoes in the direction of each blue arrow and exactly one domino in the direction of each black arrow, or vice versa(blues see one, blacks see two). There must be a region border in the middle of each domino pointed by arrow.

Solve online: Sudokupad

Hints:

• For break-in，18 friendly numbers mean there can be no friendly numbers on the diagonal(from r1c1 to r9c9).
• For the end, if you have identified all friendly numbers and determined which ones are in the same region, you next need to find 1, 7 pair in column 6(at r3c6 and r6c6). Therefore, the number 8 in column 6 is in the topmost region. Then, find 1, 8 pair in column 7(at r3c7 and r4c7). So, where is the missing number 2 in the bottommost region of column 8?

Enjoy!