Level 255 solution

Solver-verified route

1. Place Piece 1 across column 5 row 5, column 6 row 5, column 6 row 6.
2. Place Piece 2 across column 1 row 8, column 2 row 8, column 3 row 8.
3. Place Piece 3 at column 7, row 6.
4. Place Piece 6 at column 6, row 7.
5. Place Piece 4 across column 3 row 1, column 3 row 2, column 3 row 3, column 3 row 4.
6. Place Piece 5 across column 6 row 1, column 6 row 2.
7. Place Piece 7 across column 5 row 1, column 4 row 2, column 5 row 2.

Part of the "Master columns" chapter. The solver certified 1000+ solving lines with 87% of in-between placements being dead ends, for a difficulty score of 19.7 (grade 5 of 5).