Blocked Crossing
Bridges can never cross — a connection that would cross an existing bridge is impossible.
How it works
- 1A bridge already spans the middle row, from the 2 on the left to the 2 on the right.
- 2Bridges may never cross, so the 1 at the top and the 1 at the bottom can never be joined to each other — that vertical path is dead.
- 3Each of them takes its single bridge from its other neighbour instead: the top 1 from the corner to its left, the bottom 1 from the corner to its right.
- Existing bridge
- Connection ruled out
- Islands that establish the pattern