Sudoku

What distinguishes a 'diagonal' Sudoku from a regular one?

In a diagonal Sudoku, in addition to the regular rules, the two main diagonals must also contain 1-9 once.

Why are some cells shaded in certain Sudoku puzzles?

Shaded cells, often found in variants like “Center Dot” or “Asterisk”, add extra constraints or patterns to solve.

What's a 'naked pair' in Sudoku strategy?

A 'naked pair' occurs when two cells in a row, column, or box have only the same two possible numbers. These numbers can be eliminated from other cells in that unit.

Is it possible to solve every Sudoku without guessing?

Yes, every valid Sudoku has a logical pathway to its solution. Guessing is not necessary when applying the right techniques.

How does the 'swordfish' technique work in Sudoku?

The 'swordfish' is a technique that deals with candidates that appear exactly three times in rows OR columns. When these align correctly, other candidates can be eliminated.

Can a Sudoku have multiple solutions?

A well-constructed Sudoku should only have one solution. Multiple solutions suggest the puzzle isn’t crafted properly.

What’s the significance of 'givens' in Sudoku?

Givens' are the numbers pre-filled in the puzzle. They provide the starting point and their placement determines the puzzle's difficulty.

How does the 'X-wing' strategy help in solving Sudoku?

The 'X-wing' focuses on two rows and columns. When two numbers can only fit in the exact two columns in those rows (or vice-versa), they can be removed elsewhere.