Datasets:

LKForge
/

sudoku-solver-benchmark

license: mit
pretty_name: Sudoku Solver Benchmark (backtracking vs MRV vs constraint propagation)
language:
  - en
tags:
  - sudoku
  - solver
  - backtracking
  - constraint-propagation
  - mrv-heuristic
  - benchmark
  - search
task_categories:
  - other
size_categories:
  - n<1K
configs:
  - config_name: strategies
    data_files: data/sudoku-strategies.json

Sudoku Solver Benchmark — Backtracking vs MRV vs Constraint Propagation

Search cost (recursive calls / "nodes") and solve time for three ways to solve a 9×9 Sudoku, measured on the same shipped engine that powers the LK Forge Sudoku Solver, across a reproducible, seed-generated corpus of easy → expert puzzles. All three strategies are asserted to return the same correct solution, so no wrong number ships.

How the solver works: https://lkforge.com/tools/puzzles/sudoku-solver/how-the-sudoku-solver-works.html
Try it: https://lkforge.com/tools/puzzles/sudoku-solver/
Producer: LK Forge — client-side AI games, solvers, and tools.

Headline numbers (overall averages)

Strategy	Avg search nodes	Avg solve time
Naive backtracking (next-empty cell)	28,835	2.536 ms
MRV backtracking (most-constrained cell first)	177	0.220 ms
Constraint propagation (naked + hidden singles)	2	0.118 ms

So the MRV heuristic cuts search ~163× vs naive backtracking, and constraint propagation solves a typical puzzle in ~2 nodes — deducing the answer with almost no guessing, the same reasoning the solver's hint engine explains.

Files

data/sudoku-strategies.json — per-difficulty (easy/medium/hard/expert) and overall avgMs and avgNodes for each of the three strategies.

Method

Corpus: puzzles produced by the shipped generator with fixed seeds → reproducible.
Node count = recursive solver calls (a machine-independent measure of search effort).
Strategies: (1) naive backtracking in the shipped cell order; (2) MRV — always branch on the cell with the fewest candidates; (3) logic — apply naked + hidden singles as far as possible before guessing.
Correctness gate: all three must return the identical, valid solution for every puzzle.

Reproduce

node benchmark.js   # runs the shipped engine.js over the seeded corpus

Citation

LK Forge (2026). Sudoku Solver Benchmark — Backtracking vs MRV vs Constraint Propagation. https://lkforge.com/tools/puzzles/sudoku-solver/

Everything runs client-side, no login, no tracking.