Clue of One
A clue of 1 means the tallest building is visible right at that edge — place the max height there.
How it works
- 1The 1 on the left edge says exactly one building is visible looking along the top row.
- 2That's only possible if the very first building is the tallest — everything behind the 4 is hidden.
- 3Place the 4 right at the edge.
- Relationship — The arrow shows which cells support the deduction.
- Conclusion — The final arrow lands beside the proved or ruled-out height.