Extreme Sudoku 3, puzzle 44: step-by-step solution
Step through the whole solution, or skip to the hard parts. Blue digits are placed by the walkthrough; red strike-through marks a candidate being ruled out.
Blue digits are placed by the walkthrough. Red strike-through marks a candidate being ruled out. Cells are named by row and column: R3C5 is row 3, column 5. Arrow keys step too.
The key technique: Nice Loops/AICs
An alternating chain of strong and weak links. Whichever end is true, the conclusion holds, so the digit at the marked cell is ruled out.
Other advanced and expert techniques in this solve: ALS-XZ (×2), Cell Forcing Chains, Empty Rectangle, Finned Fish, W-Wing, XY-Chain.
Every move above the basics is listed on the sudoku techniques page, each with a one-sentence explanation and worked examples from the books.
The hard steps, in text (9)
- Step 11 · Empty Rectangle advanced
Rules out 8 from R3C3. - Step 12 · Finned Fish expert
Rules out 2 from R1C4. - Step 13 · Cell Forcing Chains expert
Rules out 8 from R3C2. - Step 17 · Nice Loops/AICs expert
Rules out 2 from R3C8. - Step 19 · W-Wing advanced
Rules out 9 from R4C4, R7C6. - Step 21 · ALS-XZ expert
Rules out 3 from R5C1. - Step 23 · ALS-XZ expert
Rules out 2 from R7C9. - Step 26 · Nice Loops/AICs expert
Rules out 9 from R1C4. - Step 28 · XY-Chain expert
Rules out 4 from R2C9.
The book
Volume three: 150 new classic 9×9 grids, none repeated from books 1 or 2, ramping from hard to brutal.
150 new puzzles. Expert and beyond. Puzzles by M. J. Bailey. Paperback, 5 × 8 in, 196 pages, £9.99 / $11.99. Every solution in the book carries a QR code to its own walkthrough, so you can check one step without seeing the whole answer.
Try a free sample puzzle (PDF) · prints on A4 or US Letter
More step-by-step solutions: Extreme Sudoku 1 · Extreme Killer Sudoku 1 · Extreme Sudoku 2 · Extreme Killer Sudoku 2 · Extreme Killer Sudoku 3.