or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s)
Author/Opus: This is the 140th puzzle from our contributing puzzlemaster Prasanna Seshadri.
Rules: Draw a single closed loop that passes vertically and horizontally through all cells. The loop must go through all of the given dots. When passing through a white dot, the number of cells on one side of the dot before turning must differ by 1 from the number of cells on the other side before turning. When passing through a black dot, the number of cells on one side of the dot before turning must be twice the number of cells on the other side before turning. (Not all possible dots are given; if a line crosses two dots, ignore the other dot and count cells as if it is not there.)
Also, see 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.
Time Standards (highlight to view): Grandmaster = 4:00, Master = 5:45, Expert = 11:30
Note: Follow this link for other less common Loop variations.