Sudoku Strategy Guide: Four Basic Strategies and Reasoning Methods (with Example Tutorial)

 

Sudoku, as a classic number game, attracts the interests and challenges of countless people. In this game, players need to fill a 9x9 square so that the numbers 1 to 9 appear exactly once in each row, column and each 3x3 small square. Although Sudoku may seem simple, solving puzzles requires some basic skills and reasoning to unravel the mystery.

This article will introduce some basic skills and reasoning methods commonly used in solving Sudoku to help beginners establish a foundation for solving problems. I will introduce the basic strategies of one-way scanning, two-way scanning, candidate-finding and vacancy-finding one by one, and guide readers to apply these strategies in a clearer way with demonstrations.

Commonly used basic skills and reasoning methods

When solving Sudoku, some basic skills and reasoning methods are commonly used and essential! These techniques and methods can help us solve problems more effectively. Here are some commonly used basic techniques and reasoning methods:

• One-way scanning method: Help us quickly locate candidate numbers and continue to follow-up reasoning.
  
  
• Two-way scanning view: This method combines one-way scanning view and reasoning of candidate numbers, which can provide more comprehensive information and speed up the problem-solving process.
  
  
• Find Candidates: This method is based on reasoning about the candidate numbers in each cell. By looking for unique candidate numbers in each cell, we can determine the location of these candidate numbers and thus infer the numbers in other cells. This method is often used to solve more difficult Sudoku boards .
  
  
• Find the vacancy method: This method finds the vacant positions that have not been filled by observing the numbers that have been filled in each row, column, and each 3x3 small square.
  
  
  

The above is a brief description of the four basic strategies that are commonly used. In the next article, I will provide a demonstration board and solve problems based on these strategies!

Tahoe Sudoku

Sudoku can be played in different formats, including newspapers, books, and various Sudoku applications.

I downloaded  the Tahoe Sudoku APP. This game is specially designed for beginners . It provides a choice of puzzles with multiple difficulty levels, from beginner to expert level , which can meet the needs of different players!

Although there are many Sudoku games of the same type now, and there are many versions full of special effects animations and colorful functions, I personally prefer Sudoku games with a simple interface. There are no unnecessary special effects and animation interference, so that I can focus on the process of solving Sudoku puzzles, as if I were in the newspaper to solve the problem.

🌟Tahoe Sudoku APP game features:

• New games anytime.
• Automatic error checking.
• Turn on note mode and take notes like you would on newsprint.
• Mark unique numbers in the same row, column and block.
• Hints can help you find the right answer.
• Delete wrong answers.
• Difficulty can be selected: Easy, Medium, Hard.
  
  

Go here: Tahoe Sudoku Sudoku, Classic Sudoku Puzzles, Puzzle Quests

Sudoku Problem Solving Demonstration

💡The Sudoku difficulty of the demonstration questions is "intermediate"
APP provides puzzles with multiple difficulty levels, from beginner to expert level!

Scanning every row, column, and house of numbers is a basic and easy-to-learn technique when solving Sudoku puzzles. This technique helps us to rule out impossible numbers and find the only suitable number in each square. This scanning technique is the fastest and most efficient way to solve simple Sudoku puzzles .

1. Two-way scanning view：

In the first example, we notice that the 6 in the 7th house and the 9th house are shown.

The 6 of the 7th house is on the 3rd row
The 6 of the 9th house is on the 2nd row

This also means that the 6 in the 8th house cannot be on the 2nd and 3rd row.

So the 6 in the 8th house can only be placed in the space in the first row.

However, square f3 already has 6, so column f cannot contain any more 6. So d7 is the only place where the number 6 is filled in the grid.

Two, one-way scanning view：

Next, we observe the numbers in the grid of f7.

The 5 of the 7th house is on the 2nd row, and the 5 of the 9th house is on the 3rd row, which means that the 5 of the 8th house cannot be placed on the 2nd and 3rd row , so the 5 of the 8th house can only be placed on the 3rd row. spaces on line 1.

3. Find the candidate method:

Let's look at the square g5 in the example below. There are already numbers 3, 2, 4, 1, 7 in the grid where g5 is located , 5 and 2 are located in the same row, and 5, 2, 8 are located in the same column.

Excluding all the above numbers, g5 can only be filled with 6.

Fourth, find the vacancy method:

This method is usually used in the procession houses that are almost completed.

Let's look at line 7, the known numbers are 1, 6, 9, 5, 8.
The numbers that have not been filled in are: 2, 3, 4, 7.

It can be seen from the picture that according to the principle of non-repetition, only 4 can be filled in C7.

There are still numbers that have not been filled in: 2, 3, 7.

According to the current grid, h7 can only be filled with 3 (because there are already 2 and 7 in the same column).
And so on to get the answer: a7 is 7, i7 is 2. 

According to the above problem-solving strategy, you can complete the Sudoku puzzle, try it out!

Summarize

This article introduces the basic techniques and reasoning methods commonly used when understanding Sudoku. First of all, we mentioned the one-way scanning method and the two-way scanning method. These two methods have different directions and considerations when observing and analyzing Sudoku boards. We then introduce Candidate Finding and Gap Finding, strategies that help us infer numbers in other squares based on known numbers and rules.

If you want to train your brain by solving puzzles through games, Sudoku is definitely a very suitable choice. It's convenient, fun, and endlessly challenging and intellectually exercising. Come and try the fun of solving puzzles!

Go here: Tahoe Sudoku Sudoku, Classic Sudoku Puzzles, Puzzle Quests