Linesweeper (Transparent) by Prasanna Seshadri
or solve online (using our beta test of Penpa-Edit tools in lineox mode where left click+drag draws lines and left click in square marks O and X.)
Theme: Clue Symmetry and Logic (originally on 2016 Polish Puzzle Championship)
Author/Opus: This is the 121st puzzle from our contributing puzzlemaster Prasanna Seshadri.
Rules: Draw a single closed loop (without intersections or crossings). Each clue gives the number of surrounding clues used by the loop. The loop can pass through the clue cells.
See also this example:
Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. If the loop only has vertical segments in the marked row, enter 0. Separate each row’s entry with a comma.
Solution: PDF
Time Standards (highlight to view): Grandmaster = 3:15, Master = 5:30, Expert = 11:00
11:01