The Hidden Border

Black out the boxes of this 16 × 16 grid to satisfy all series.

Materials: Pencil and gum; grid below.

Rules you need

A series shows the lengths of the consecutive black blocks in the order, from left to right for a line and from top to bottom for a column.
Two adjacent blocks are separated by at least one empty box. Non-blacked boxes must remain empty. "0" indicates a completely empty line.
The LrCc coordinates refer to line r, column c, counted from the upper left corner.

The puzzle

The series and possible pre-filled boxes are the only data of the problem. ■ = already black box, · = already proven empty box; the white boxes without symbol remain unknown. No symmetry or recognizable image should be assumed.

Coordinates: lines from top to bottom, columns from left to right.
L / C	C94311	C1141111	C122111
L11 · 3 · 3 · 1 · 1
L29 · 1
L32 · 1 · 1 · 1 · 3
L42 · 1 · 1 · 1 · 3 · 2
L52 · 2 · 1 · 1 · 2
L65 · 3 · 2		■
L72 · 3 · 2 · 2 · 1
L81 · 2 · 5 · 2			·
L91 · 2 · 1 · 1 · 1
L101 · 1 · 1 · 2 · 3
L112 · 2 · 1	·
L121 · 1 · 1 · 1 · 2
L131 · 2 · 1 · 2 · 1
L141 · 1 · 1 · 1 · 3
L151 · 3
L161 · 3 · 1

Why this level?

The simple intersection blocks; the crosses require an intertwined case analysis (depth 10, 16 impossible branches in the solver). Editorial level based on this need for coordination, not on the only format of the grid.

Your workspace

Write down your assumptions separately from deductions you have proved.

Notes for SOLO-024

View the solution to SOLO-024 →