This puzzle has been constructed as training for LM 2022.
Rules: Blacken some cells of the diagram, such that any non-blackened arrow points to the correct number of black cells. Black cells cannot touch each other orthogonally. Draw a closed loop through every remaining empty cell, which goes horizontally and vertically from cell to cell. Not all black cells need to be pointed at.
Solution code: Row 2 and row 9: I for a straight line, L for a corner, X for a black cell