Friday · Setter: M. Vantablack
1842
The Diagonal Confession
Thirty givens, one solution, and exactly one place where the logic stops being polite. Column 5 is where most solvers put the kettle on.
Specification
- GradeHard · 4 of 5
- Givens30
- Symmetry180°
- Par time21:40
- Solutions1
The Grid · 9 × 9 · 3 × 3 boxes
R— C— · box —
Select a cell, then type 1–9. Shift+digit writes a pencil mark.
30 / 81 placed
Solve log
Every placement is recorded with its coordinate, the digit, and the box it landed in. Pencil marks are logged separately so you can audit the guess that cost you four minutes.
| # | Time | Cell | Act | Box |
|---|---|---|---|---|
| No moves yet — the grid is exactly as the setter left it. | ||||
Technique notes
Four passes will finish this grid. The setter recommends taking them in order and resisting the urge to guess at step three.
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1
Scan the stacks
Work band by band. Any digit appearing twice in a stack of three boxes pins its third occurrence to a single column.
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2
Pencil everything in box 5
The centre box carries the puzzle. Write the full candidate set in micro type before you place a single digit.
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3
Naked pair, rows 4 & 6
Two cells sharing the candidates {2,7} eliminate both digits from every other cell in the row. This is the confession.
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4
Cascade
From there the grid falls in roughly forty placements. Keep the pencil marks — they are the proof, not the scaffolding.