EXTREMEPUZZLE BOOKS

Extreme Sudoku 2, puzzle 96: 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.

Puzzle
Sudoku, number 96 of 150 in Extreme Sudoku 2
Difficulty
Expert 5 (expert and beyond), from the middle third of the book
Key technique
Nice Loops/AICs
Hard steps
16 of 41 steps need an advanced or expert technique

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 (×3), Finned Fish (×2), X-Wing/Swordfish (×2), 2-String Kite, Cell Forcing Chains, XY-Chain, XYZ-Wing.

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 (16)
  1. Step 6 · 2-String Kite advanced
    Rules out 6 from R1C8.
  2. Step 7 · Finned Fish expert
    Rules out 6 from R1C7.
  3. Step 8 · Finned Fish expert
    Rules out 9 from R2C4.
  4. Step 9 · ALS-XZ expert
    Rules out 3 from R7C4.
  5. Step 11 · Nice Loops/AICs expert
    Rules out 2 from R1C8.
  6. Step 12 · Nice Loops/AICs expert
    Rules out 2 from R4C7.
  7. Step 13 · Nice Loops/AICs expert
    Rules out 8 from R8C2.
  8. Step 16 · Nice Loops/AICs expert
    Rules out 2 from R8C5.
  9. Step 17 · Nice Loops/AICs expert
    Rules out 6 from R3C6; 1 from R6C6.
  10. Step 19 · XYZ-Wing advanced
    Rules out 2 from R2C3.
  11. Step 21 · Cell Forcing Chains expert
    Rules out 5 from R1C8.
  12. Step 25 · X-Wing/Swordfish advanced
    Rules out 6 from R1C1, R1C2, R1C6.
  13. Step 26 · ALS-XZ expert
    Rules out 8 from R6C1.
  14. Step 27 · ALS-XZ expert
    Rules out 6 from R8C8.
  15. Step 34 · X-Wing/Swordfish advanced
    Rules out 2 from R1C1, R1C5, R3C1, R6C1.
  16. Step 37 · XY-Chain expert
    Rules out 5 from R1C7, R3C2.

The book

Volume two: 150 new classic 9×9 grids, none repeated from book 1, 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.

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More step-by-step solutions: Extreme Sudoku 1 · Extreme Killer Sudoku 1 · Extreme Killer Sudoku 2 · Extreme Sudoku 3 · Extreme Killer Sudoku 3.