Queens answer. #921
Queen positions
Rows and columns below start at 1, from the top left.
- Row 1: column 7.
- Row 2: column 5.
- Row 3: column 8.
- Row 4: column 3.
- Row 5: column 9.
- Row 6: column 2.
- Row 7: column 4.
- Row 8: column 6.
- Row 9: column 1.
Why it works
The small region in row 1 spans columns 6–7, so its queen must be in that row; the solution chooses column 7. Reading down the nine rows, the queen columns are 7, 5, 8, 3, 9, 2, 4, 6 and 1. Each column appears once and the queens occupy nine different coloured regions. Neighbouring rows differ by at least two columns, so none of the queens touch diagonally.
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