Skyscraper
AdvancedUsed at: Expert
A candidate appears in the same row across two columns, creating cross eliminations. A variation of X-Wing.
Skyscraper — Explained
Skyscraper is an X-Wing variant. When two rows each have a digit in exactly two positions, and one aligns on the same column, you can eliminate at the intersection of the opposite ends.
When to Use
When X-Wing doesn't quite form but you still want strong eliminations. Works alongside X-Wing.
Common Mistakes
Getting elimination direction wrong. The 'top' intersections are the elimination targets.
Tips
When looking for X-Wing, if the columns don't align, it might be a Skyscraper.
Skyscraper Steps
Find in 2 rows
Find a digit with exactly two positions in each of two rows.
Check alignment
One pair shares the same column (base). The other pair are the tops.
Eliminate at intersection
The cell where the two tops intersect is your elimination target.