Binary Puzzles - 400 Hard to Master Puzzles 9x9 Vol.6 - David Smith - Bog

Binary (also known as "Binairo Puzzle," "Takuzu," "Tohu wa Vohu") is played on a rectangular or square grid. The goal is to fill in the grid with digits "0" and "1" according to the following rules: Each box should contain a zero or a one.No more than two similar numbers next to or below each other are allowed.Each row and each column should contain an equal number of zeros and ones (or one more for odd sized grids).Each row is unique, and each column is unique.