sudoku-solver-wasm

A fast Sudoku solver compiled to WebAssembly from C.

The solving logic is written in C using a backtracking algorithm and compiled to WASM via Emscripten. The JS layer is a thin wrapper that handles input/output conversion — no runtime dependencies.

Install

npm install @edracoon/sudoku-solver-wasm

Usage

import { solve } from '@edracoon/sudoku-solver-wasm';

solve(grid) accepts either a 2D array or a flat 81-character string and always returns a number[][], or null if the puzzle has no solution or the input is invalid (wrong length, invalid characters).

// 2D array input
const solved = solve([
    [0, 1, 0, 0, 0, 0, 0, 6, 9],
    [4, 0, 6, 0, 0, 0, 0, 7, 5],
    [7, 0, 0, 0, 0, 0, 0, 0, 0],
    [0, 0, 0, 0, 7, 0, 4, 0, 0],
    [1, 0, 0, 0, 2, 0, 0, 0, 0],
    [3, 0, 0, 5, 0, 1, 9, 0, 0],
    [0, 2, 7, 0, 0, 3, 0, 0, 0],
    [0, 0, 0, 9, 0, 0, 0, 0, 7],
    [0, 0, 9, 0, 0, 0, 8, 0, 0]
]);

// Flat string input
const solved = solve('687004910913000000254700000045090001006105040000000200400560030002473090508921704');

Or use solveFlat() with the same inputs if you need the result as a flat string instead of a 2D array.

How it works

The solver is written in C and uses a classic backtracking algorithm:

1. Find the first empty cell (0)
2. Try each digit 1–9, checking row, column, and 3×3 box constraints
3. Recurse — if no digit fits, backtrack and try the next one

Build from source

Requires emsdk and Node.js 22+.

npm install
npm run build