How to Solve Sudoku, in 10 Steps
Audio Brief
Show transcript
This episode introduces a systematic, 10-step method for solving Sudoku puzzles of any difficulty by treating them as an information management problem.
There are four key takeaways from this discussion. First, shift from intuition to a structured information management approach for Sudoku. Second, utilize a custom worksheet to track all possibilities across the grid. Third, the core solving technique involves an iterative process of identifying and placing "unique" numbers. Finally, recognize "uniques" as either a cell's last remaining possibility or a group's sole placement for a specific number.
The method emphasizes a disciplined, systematic approach over relying on intuition. This foundational philosophy redefines Sudoku as a problem of managing and updating information rather than guessing or sporadic deduction.
A custom worksheet is central to this system. It provides a visual framework to track all potential numbers for every cell, box, row, and column simultaneously. This externalized information significantly reduces cognitive load and reveals deductions more clearly.
Solving progresses through an iterative cycle of elimination and placement. Once a number is confidently placed, that information is immediately used to eliminate it as a possibility from all affected cells in its row, column, and 3x3 box. This systematic reduction continuously uncovers the next solvable number.
"Uniques" are the primary mechanism for advancing the puzzle. A unique is found when a cell has only one remaining possible number. Alternatively, a number is unique if it can only be placed in one specific cell within its row, column, or 3x3 box, even if that cell has other possibilities.
This methodical approach ensures a reliable, step-by-step process for solving Sudoku puzzles efficiently and accurately.
Episode Overview
- The episode introduces a systematic, 10-step method for solving Sudoku puzzles of any difficulty, presented by Dr. Anadale of Mount St. Mary's.
- The host explains his core philosophy of treating Sudoku as an "information management problem," which is facilitated by a custom worksheet.
- The worksheet is designed to track all possible numbers for each individual cell, as well as the remaining possibilities for each 3x3 box, row, and column.
- The 10-step system involves an initial setup phase (transferring given numbers and eliminating obvious impossibilities) followed by an iterative process of identifying "uniques" to solve the puzzle.
- The episode concludes by beginning a demonstration of the method on an easy-level Sudoku puzzle, showing the initial setup steps in action.
Key Concepts
- Sudoku as an Information Management Problem: The central idea is to shift away from intuition and towards a structured system for tracking and updating information about every part of the puzzle grid.
- The Worksheet System: A custom-designed grid is the key tool for this method. It allows the solver to visualize all potential numbers for every cell, box, row, and column at once, making it easier to spot deductions.
- Identifying "Uniques": The primary solving technique revolves around finding "uniques." This refers to either a cell that has only one possible number left (a naked single) or a larger group (box, row, or column) where a specific number can only go in one available cell (a hidden single).
- Iterative Elimination Process: The system is a cycle. Once a number is placed in a cell (a "unique" is found), that new information is used to eliminate that number as a possibility in the corresponding row, column, and box. This reduction of possibilities helps reveal the next unique number, continuing the cycle until the puzzle is solved.
Quotes
- At 00:19 - "My system treats Sudoku like an information management problem." - The speaker explains the fundamental principle behind his method.
- At 00:42 - "This is the worksheet that I have created to go with my Sudoku method." - Introducing the central tool used to organize and track information throughout the solving process.
- At 01:52 - "Scan every cell in the worksheet looking for cells that have just one number left. We'll call these uniques." - Defining the key term "uniques" and outlining the first major solving step after the initial setup.
- At 02:17 - "What you're doing is exporting that information from the filling of that cell into the other boxes and columns of the worksheet." - Explaining the crucial process of updating the entire grid after placing a single number.
- At 03:01 - "It's very important to follow this step one cell at a time. Don't go chasing down rabbit holes." - Emphasizing the need for a methodical, step-by-step approach rather than jumping around the puzzle without a clear process.
Takeaways
- Adopt a systematic approach to solving Sudoku by treating it as an information management challenge, which can be more reliable than pure intuition.
- Use a worksheet to track all possibilities. This externalizes the information, reduces mental load, and makes it easier to spot patterns and necessary deductions.
- The core of the method is a cycle: find a number that can be definitively placed, fill it in, and then exhaustively update all affected rows, columns, and boxes by eliminating that number as a possibility elsewhere.
- There are two primary ways to find the next number to place: identify a cell where only one number is possible, or identify a group (box, row, or column) where a number must go in a specific cell because it's impossible anywhere else in that group.
