Forced Expansion
An island blocked everywhere but one open cell has no other way to grow — that cell joins it.
How it works
- 1The 4 has only itself so far, so it still has to grow three more cells somewhere.
- 2It sits on the top edge, and sea already blocks it to the left and below.
- 3That leaves exactly one open neighbor, so the island has no choice — that cell is land.
- Island (land)
- Sea
- Cells that establish the pattern
- Where the conclusion lands