Mirrored from Sudopedia, the Free Sudoku Reference Guide

# Solving path

A solving path or walkthrough is a list of steps that shows how a particular puzzle is solved.

Depending on the writer and the intended audience, some basic solving techniques may be omitted from the list. Most players know how to locate singles and these are usually skipped. In exchanges between advanced players, the SSTS steps are also skipped, with a marker showing where they are used in the solving path. Similarly, the final stages of solving a puzzle are often omitted, since the last few placements of digits in the puzzle usually require only basic knowledge of the rules of Sudoku.

There are many ways to solve a single puzzle. Sometimes different solving techniques cause the same eliminations, but there are often alternative steps which lead to a different solving path, even when the same set of techniques is used. The choice between two Naked Pairs can have a lasting effect on the remainder of the solving path. In Killer Sudoku, the number of alternatives is even greater, because the player can choose to use standard Sudoku techniques as well as the techniques especially developed for the Killer variant.

The milestones in a solving path are often illustrated with an annotated pencilmark grid.

Many computer solving programs will generate a "solving log" (a list of the steps the computer performed in the process of solving the puzzle), which is in essence a walkthrough. However, in the case of complex puzzles (especially Killers), these logs typically contain many unnecessary steps or logical dead-ends, and so they are much more difficult for humans to follow than a human-generated walkthrough.

## Rating a puzzle

The rating of a Sudoku puzzle is usually expressed as the difficulty of the solving techniques needed in the easiest solving path for that puzzle. However, there is controversy in how to rate solving paths. For a given puzzle, there may exist a solving path that applies a single instance of a very difficult technique and only elementary techniques for the remainder of the path, and another solving path that uses moderately difficult techniques throughout the path. So far, there appears to be no consensus on how such puzzles should be rated.