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or solve online (using our beta test of Penpa-Edit tools; click on a cell to cycle between a white circle, a black circle, and an empty cell).

Theme: Logical

Author/Opus: This is the 23rd puzzle from our contributing puzzlemaster Ashish Kumar.

Rules: Fill some cells with either a single white or black “stone” so that there is exactly one black stone in each row and column. Digits on the outside indicate the count of stones in that row/column up to and including the black stone.

See also this example:

Answer String: Enter the contents of the 4th row from left to right, followed by a comma, followed by the 6th row from left to right. Use a capital B for a black stone, a capital W for a white stone, and a capital X for a blank cell.

Time Standards (highlight to view): Grandmaster = 1:00, Master = 1:30, Expert = 3:00

Solution: PDF