Guided Hints look for a logical next step in the current grid. Instead of immediately revealing an answer, a hint names the technique, focuses attention on the relevant cells, and explains either the placement or candidate elimination.
Open the hint menu while playing and choose Guided Hint. If the technique needs candidates and some are missing, Lab Sudoku can populate them before continuing.
Reading a visual hint#
The board uses visual emphasis to separate the parts of a pattern:
- accent candidates form the logical pattern;
- red candidates can be removed;
- lines show candidates that are linked by the technique.
Cell positions can be shown as row-and-column coordinates such as R3C5, or in chess-style notation such as E3, depending on your settings.
Placement techniques#
Naked Single#
A cell has only one possible candidate, so that digit must be placed there.
Hidden Single#
A digit may appear as a candidate in several cells generally, but in one particular row, column, or box it has only one possible position.
These single techniques are included in the free Guided Hint set.
Subset techniques#
Naked Pair and Naked Triple#
Two or three cells in a unit contain only the same two or three candidates. Those candidates can be removed from other cells in that row, column, or box.
Hidden Pair and Hidden Triple#
Two or three digits can only appear in the same two or three cells of a unit. Other candidates can be removed from those selected cells.
Box-line interactions#
Pointing Pair or Triple#
Within one 3×3 box, all candidates for a digit lie in the same row or column. That digit can be removed from the rest of that row or column outside the box.
Claiming#
Within a row or column, all candidates for a digit lie in a single box. The digit can be removed from other cells in that box.
Wings and fish#
XY-Wing#
Three two-candidate cells form a linked pattern. Any cell that sees both wing cells cannot contain the shared elimination candidate.
X-Wing#
A digit is restricted to the same two columns in two rows—or the same two rows in two columns. Other occurrences in those columns or rows can be removed.
Swordfish#
Swordfish extends the X-Wing idea across three rows and three columns, allowing the same candidate to be removed outside the pattern.
Advanced Guided Hint techniques and their visual explanations are Premium features. You can always choose Reveal Digit when you want an answer rather than a logical explanation.