or solve online (using our beta test of Penpa-Edit tools; in default linex mode: left-click+drag draws line, right click marks X on edge)
Theme: Speed of Light and Speed of Sound
Author/Opus: This is the 20th puzzle from guest contributor Bryce Herdt.
Rules: Draw a single loop in the grid which may cross itself orthogonally, but otherwise does not touch or retrace itself. The clue numbers to the left/right of the rows indicate the number of squares visited by the nearest section of the loop that travels horizontally in the rows. The clue numbers to the top/bottom of the columns indicate the number of squares visited by the nearest section of the loop that travels vertically in the columns.
Also, see this example:
Difficulty: 3 stars
Time Standards (highlight to view): Grandmaster = 2:45, Master = 5:15, Expert = 10:30
Solution: PDF; a solution video is also available here.
Note: Follow this link for other Round Trip puzzles. Some more Round Trip puzzles can be found in the book Loop Variety Collection by Ashish Kumar and Murat Can Tonta.