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Level 16 guide: Indonesia (hard)

Over seventeen thousand islands. A 9×9 board. Colors are named in the steps below, and rows and columns are counted from the top left starting at 1. This guide spoils the solution, so try the level first.

Play level 16

The board

Step by step

15 deductions lead to the 9 stamps. Each placed stamp also rules out its row, column, touching cells and the rest of its region.

1. The peach region can only hold its stamp in column 9, so every other cell in column 9 cannot hold a stamp (5 cells ruled out).
2. Columns 1 and 2 must all put their stamps in the amber region and the pink region, so the other cells of the amber region and the pink region cannot hold a stamp (15 cells ruled out).
3. Column 3 has only one cell left: row 8. Place the stamp there.
4. The stone region can only hold its stamp in row 9, so every other cell in row 9 cannot hold a stamp (2 cells ruled out).
5. The pink region can only hold its stamp in column 1, so every other cell in column 1 cannot hold a stamp (5 cells ruled out).
6. The pink region and the peach region must all put their stamps in rows 6 and 7, so every other cell in rows 6 and 7 cannot hold a stamp (6 cells ruled out).
7. Column 4 has only one cell left: row 3. Place the stamp there.
8. The periwinkle region can only hold its stamp in row 5, so every other cell in row 5 cannot hold a stamp (3 cells ruled out).
9. Column 5 has only one cell left: row 1. Place the stamp there.
10. Column 6 has only one cell left: row 4. Place the stamp there.
11. The amber region has only one cell left: row 2, column 2. Place the stamp there.
12. The periwinkle region has only one cell left: row 5, column 8. Place the stamp there.
13. The peach region has only one cell left: row 7, column 9. Place the stamp there.
14. The pink region has only one cell left: row 6, column 1. Place the stamp there.
15. The stone region has only one cell left: row 9, column 7. Place the stamp there.

Final solution