Binairo

Hard Binairo uses a 10×10 grid with 100 cells. Each row and column needs five 0s and five 1s. Every puzzle requires at least one T3 uniqueness deduction: T1 and T2 techniques alone cannot solve it.

T3 reasoning works from the uniqueness rule: no two rows (or columns) can be identical. If two rows share the same digits in every filled position and only differ in a few empty cells, those cells must be filled to keep the rows distinct. The key is scanning for near-duplicate rows or columns when consecutive forcing and look-ahead have run out.

Hard puzzles are solvable without guessing. If you feel stuck, compare rows against each other — the uniqueness constraint is almost always the next breakthrough.