mohaps / Sudoku

A C++ Sudoku Solver with no dependencies (DFS with Backtracking)

Sudoku Solver (C++)

A C++ Sudoku Solver with no dependencies. Weekend hack and programming practice. Solves the sudoku puzzle via Depth First Search / Backtracking.

Algorithm

• create a queue of all empty cells in the board as candidates
• initiate offset into the candidates list as 0
• for each permissible value that can be set in the first candidate
  • offset is incremented by 1
  • try each permissible value in next candidate
  • loop till out of candidates or puzzle solved

Worst Case Runtime Complexity: O(9^k), where k is the number of empty cells left to solve

The implementation is in src/sudoku/Solver.cpp in the solveWithCandidates() method

Implemented a Check9 class to check if 1-9 is set in row/column or 3x3 grid

TODO

• implement board generator
• implement interactive console game

Build

to compile:

make

this will provide bin/sudoku_solver if everything goes well

to compile and run:

make run BOARD_FILE=<board-file-name>

e.g

make run BOARD_FILE=data/expert2.sudoku

Usage

general usage:

bin/sudoku_solver <board-file-name>

sample board files included in data/

data/empty_board.sudoku
data/board1.sudoku
data/expert1.sudoku
data/expert2.sudoku

Board File Format

begins with magic header #$$sudoku-file$$# as the first line and then 9 lines each with a row of the sudoku board (digits 1-9 or . for 0/blank cell)

#$$sudoku-file$$
53..7....
6..195...
.98....6.
8...6...3
4..8.3..1
7...2...6
.6....28.
...419..5
....8..79

Credits

Saurav Mohapatra ([e-mail]) License: Apache 2.0