What are Sudoku’s hidden triplets?
As sudoku becomes more complicated every day, it is just common for different techniques to arise in order to solve a sudoku puzzle. One of the most techniques or patterns that sudoku enthusiasts use is hidden triplets. From the name itself, a hidden triple is when you have the same three digits (or a subset of them) as candidates in exactly three cells within the same row, column, or block. In addition to these three digits, you also have other possible candidates that “hide” the three digits that form the triple (otherwise, it becomes a naked triple).
How do sudoku hidden triplets works?
Image Credit : Masteringsudoku
Looking at the image on the left side, highlighted numbers 1, 7, and 8 are the only unique candidates in the three specific cells. That is what you call naked triplets, as it only happens when you have exactly three cells within a row, column, or 3×3 region where the only candidates are the same three digits. Now, look at the figure on the right side. The three highlighted cells (in red font) in this example still form a naked triple as the set of three digits (1, 7, and 8) appears as the only candidates in three cells.
So what is the difference between naked triple to hidden triple? In hidden triple, there are other possible candidates in that three cells in a row/column/3×3 block that hides the hidden triple. Look at the example figure below.
Image Credit : Learn sudoku
In the figure on the left, it is noticeable that the three cells which are highlighted