Fill the grid with 0s and 1s: no three alike in a row, equal counts in every line, no two lines the same
The binary puzzle is a grid you fill with 0s and 1s under three rules: no more than two of the same digit next to each other in any row or column, the same number of 0s and 1s in every row and column, and no two rows or two columns exactly alike. Some digits are given; you work out the rest. Every puzzle here is new, comes in 6×6, 8×8 or 10×10, and has exactly one solution that can be reached without guessing, because the generator only removes a given digit if logic alone can still finish the grid.
Choose a grid: 6×6 is easy, 8×8 is medium and 10×10 is hard.
Press New puzzle. Underlined digits are given and cannot be changed.
Tap a blank square to write 0, tap again for 1, and a third time to clear it.
On a keyboard, move with the arrow keys, type 0 or 1, and press Backspace to clear. Ctrl+Z undoes.
With Show rule breaks on, any square that is part of three in a row, an over-full line or a repeated line gets a red ring.
Fill every square so all three rules hold. The puzzle finishes the moment the grid is complete and correct, and your time is recorded.
Rule-based deduction and careful checking. Each rule is simple, but a good solve means applying all three at once across rows and columns, spotting the patterns that force a digit, and keeping count as a line fills up. The late stages, where only the no-repeated-lines rule decides a square, reward the kind of comparison between two nearly finished lines that also helps with proofreading and spotting differences in data.
Pairs: two equal digits side by side must have the opposite digit on both ends. 0 0 means 1 0 0 1.
Gaps: a blank between two equal digits must be the opposite digit. 1 _ 1 means 1 0 1.
Counting: once a line has half its squares as 0s, every other blank in it is a 1, and the other way round.
Look for a line with three blanks left where two are next to each other: often only one arrangement avoids three in a row.
Near the end, compare lines. If a nearly full row could only be finished to match a complete row, it must be finished the other way.
Use Undo freely. It steps back one change at a time, up to 200 changes.
Fill every square with 0 or 1 so that no row or column has three of the same digit next to each other, every row and column has the same number of 0s and 1s, and no two rows and no two columns are identical.
Yes. Each puzzle is dug out of a complete random grid, and a given digit is removed only if a line-by-line solver can still finish the grid from what is left. A puzzle that logic can finish has a single solution.
No. The solver that checks each puzzle only ever fills a square when every legal way of completing that row or column agrees on it, taking the finished rows and columns into account. If it could not finish, the puzzle would not be shown.
Because every line needs equal numbers of 0s and 1s. That is why the sizes are 6, 8 and 10.
It rings in red any square involved in three equal digits in a row, any digit in a line that already has too many of that digit, and any line that exactly repeats another finished line. It never tells you whether a digit that breaks no rule is the right one. Turn it off for a harder solve.
It is free with no sign-up. Your best time for each size, your number of solved puzzles and the rule-break setting are saved in this browser only.