Reusing Existing Sudoku Puzzles (How Do I Make Millions of Sudoku Puzzles?)

Whether you are having a vacation or recovering from the hospital, Sudoku is a perfect number game for you! It develops your logical reasoning ability, patience, your concentration to solve problems, and helps you build confidence.

In my earlier article “How to Design a Sudoku Within Minutes,” I talked about the idea of designing a Sudoku in the exact REVERSE WAY of solving a Sudoku. After you had finished designing a Sudoku, or you saw a classic Sudoku puzzle in a newspaper or magazine, you can use it to design tens of thousands of new Sudokus. A classic Sudoku is a Sudoku that has one and only one solution, and two symmetrical squares (If you connect two squares, its center lies in the center of the Sudoku, they are symmetrical squares) are either both filled, or both not filled with numbers. For example, today’s medium Sudoku is a classic Sudoku.

Today’s Medium Sudoku 今日数独（难度：中等）

Whether you

• Exchange the top bottom three rows and the bottom three rows;
• Exchange the left three columns and the right three columns;
• Exchange the fourth column and the sixth column;
• Exchange the fourth row and the sixth row; or
• Exchange any two numbers;

You will get a new Sudoku. The new Sudoku and the old Sudoku are intrinsically the same because they have the same constraints, and in the new Sudoku, two symmetrical squares (around the center of the Sudoku) are either both filled or not filled with numbers. You can print a new blank Sudoku, such as https://www.createclassicsudoku.com/blankgrid.jsp,  then use the above methods to get new Sudokus. Is the new Sudoku easier, as easy as, or more difficult to solve? You are welcome to discuss this with me. My email address is create.classic.sudoku@gmail.com. Below are several examples of new Sudokus based on today’s Sudoku.

Exchange the top three rows and the bottom three rows (A New Sudoku)

Exchange the fourth column and the sixth column (A New Sudoku)

Exchange digit 4 and digit 8 (A New Sudoku)

About the author: Yaling is a software programmer, Book author of Create Classic Sudoku (Available on Amazon.com), and founder of www.createclassicsudoku.com.