Skyscraper

Hard

Two conjugate pairs in different columns share one row; cells seeing both free ends can have the digit eliminated.

How It Works

For a given digit, two columns each have a conjugate pair. If one end of each pair shares the same row, the other two ends act like a Naked Pair — any cell seeing both free ends can have the digit eliminated.

Part of the "Turbot Fish" family, using basic chain logic.

Example

256
1
35
367
8
267
249
2469
469
26
4
36
1
236
9578
78945
26
1
26
3
1728
46
3
49
469
5
83
46
56
9
456
712
56
9
456
27138
46
3
25
7
59
186
249
49
4
256
8
579
26
57
29
31
9
26
1
36
2346
246
857
Key cells of the techniqueCells where elimination is appliedCandidate to be placedEliminated candidate (crossed out)

Practice with a Real Puzzle

This 9×9 puzzle is solver-verified to require this technique on its solution path.

Medium26 givens