An Easy 10×10 Puzzle Solved with Line Confinement in 14 Steps
Play this board yourself →A
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This 10×10 board rates as easy (difficulty score 564). Solving it from scratch takes 14 logical steps, using 5 techniques: Single cell, Row/column exclusion, Adjacency clear, Region confinement, Line confinement. Every step below is forced: nothing here is a guess.
- First, every open cell left in this region sits in row 6, so its marker has to land there; that clears every other open cell in the row.
- Next, place a marker at C5. Region has exactly one open cell left. Placing here clears the rest of row 5, column C, and its region. Placing here also clears its 3 touching neighbours.
- Then, place a marker at B3. Region has exactly one open cell left. Placing here clears the rest of row 3, column B, and its region. Placing here also clears its 2 touching neighbours.
- After that, place a marker at A1. Region has exactly one open cell left. Placing here clears the rest of row 1, column A, and its region.
- Now, place a marker at D7. Region has exactly one open cell left. Placing here clears the rest of row 7, column D, and its region. Placing here also clears its 2 touching neighbours.
- From there, every open cell left in this region sits in column J, so its marker has to land there; that clears every other open cell in the column.
- Following that, every open cell in row 10 belongs to the same region, so that region's marker has to be somewhere in this row; that clears every other open cell in the region.
- First, every open cell in row 9 belongs to the same region, so that region's marker has to be somewhere in this row; that clears every other open cell in the region.
- Next, place a marker at I8. Row 8 has exactly one open cell left. Placing here clears the rest of row 8, column I, and its region. Placing here also clears its 1 touching neighbour.
- Then, place a marker at F9. Region has exactly one open cell left. Placing here clears the rest of row 9, column F, and its region. Placing here also clears its 2 touching neighbours.
- After that, place a marker at H10. Region has exactly one open cell left. Placing here clears the rest of row 10, column H, and its region.
- Now, place a marker at G6. Region has exactly one open cell left. Placing here clears the rest of row 6, column G, and its region.
- From there, place a marker at E2. Region has exactly one open cell left. Placing here clears the rest of row 2, column E, and its region.
- Finally, place a marker at J4. Region has exactly one open cell left.
The key move here was Line confinement. Once you can spot that, this board falls quickly. ∎