Sudoku scan-and-solve vs hints: what should be checked first?
Scan rows, columns, and 3×3 boxes, write candidates, and place only what the current grid proves. A no-spoiler coached hint follows the same rules but narrows the next check without handing over the full answer.
One visible proof
The rules do not change. The difference is who chooses the next check and how much of the conclusion is revealed.
- What is scan-and-solve?Start with a row, column, or 3×3 box. List missing digits and cross out cells blocked by the other two units. In a basic scan, place a digit only when one legal choice remains.
- What does a no-spoiler coached hint add?The hint can point to the area, then the cell, then the reason. You still inspect the row, column, and box and make the move. The full answer is not needed for the next deduction.
- How do you verify a candidate?A candidate is legal only if its digit is absent from the cell’s row, column, and 3×3 box. After a placement, remove that digit from notes in those three units. A note is not proof until all three checks agree.
- Do you need a complete solution?No. Both approaches can work one proven move at a time. This comparison shows the checks and reasoning; it does not publish a solved grid or answer sequence.
Verify every candidate against its row, column, and 3×3 box before placing anything. The example notes are prompts for checking, not a complete answer.
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