C++ implementation: Solving a 9 × 9 Sudoku
GitHub Repo: https://github.com/tsagaanbar/sudoku-solve
https://en.wikipedia.org/wiki/Sudoku_solving_algorithms
Solving a Sudoku is an exact cover problem. However, it can be easily solved by a DFS algorithm with the help of mordern CPUs.
The implementation could be tested on Online Judge such as:
Something about the exact cover problem: