Sudoku

Rules

Place a digit from 1-9 in each empty cell in the grid such that each row, column and marked 3x3 box contains each digit exactly once.

(Rules from PGP IB, example (1-4) from WPC 2019 IB)

Rule variarions

• Common gird sizes other than 3x3 : 1-4 with 2x2 boxes, 1-6 with 2x3 boxes, 1-8 with 2x4 boxes, 1-12 with 3x4 boxes.

History of the puzzle

Although Latin squares has been known since 18th century, the introduction of boxes were first done by Howard Garns (USA). Originally named "Number Place," the puzzle was first published in 1979 by Dell Magazines.

The name 数独 ("Sudoku") was given to this puzzle by Maki Kaji in 1992, as a contraction of 数字は独身に限る, meaning "numbers are limited to being unmarried."

Variants

There are thousands of Sudoku variants. Sudoku variants are so popular that in 2006, the World Sudoku Championship separated from the WPCs. See list of Sudoku variants.

Appearances in the past WPCs

Listed here are appearances of classic Sudokus. For variants, see list of Sudoku variants#Appearances in the past WPCs.

• WPC 2019/World Cup Round 1 by Roland Voigt
• WPC 2019/Round 4 by Roland Voigt
• WPC 2016/Team Playoffs (part of combination puzzle) by Matej Uher
• WPC 2014/Round 4
• WPC 2010/Part 2