Queens Puzzle

Here's the programming problem: https://en.wikipedia.org/wiki/Eight_queens_puzzle

These are the different aspect of the project you can work on (in order):

• Determine all possible solutions for a given N where N ≥ 8 (within 10 mins on a laptop). Bonus points for a higher N where N is the size of the board / number of queens.
• Iterate over N and store the solutions in postgres using SQLAlchemy.
• Write basic tests that at least verify the number of solutions for a given N match what's online. I recommend using pytest
• Docker-ize the solution, so that I can run the code and tests without any assumption of my local setup (including running a postgres instance in docker-compose)
• setup Travis CI (or similar) for your public GitHub repo to run the tests automatically

Notes:

This solution it's based on N-Queens-Puzzle implemented by Paul Silisteanu (@sol-prog). https://github.com/sol-prog/N-Queens-Puzzle

Requirements:

• Docker.
• Docker-compose.

Install:

Clone the repository

git clone [email protected]:pixelead0/nQueensPuzzle.git

Copy the example environment variables.

cp .env.example .env

Run docker-compose to start the containers:

docker-compose up

Run

To run use: docker-compose exec app python puzzle_queen.py --help

$ docker-compose exec app python  puzzle_queen.py --help
Usage: puzzle_queen.py [OPTIONS]

  The eight queens puzzle in Python.

Options:
  -n, --pieces INTEGER  Number of queens (default=8).
  -f, --full_board      Show solutions on full NxN board.
  -s, --short_board     Show the queens positions on the board in compressed
                        form, each number represent the occupied column
                        position in the corresponding row.

  -db, --save_db        Save the solutions on database.
  -g, --get_db          Get the solutions from database (this option exclude
                        -db).

  --help                Show this message and exit.

Usage examples :

# Calculate 8 queens and show solutions on 8x8 board without save on database.
docker-compose exec app python  puzzle_queen.py --full_board

# Calculate 10 queens and show solutions on 10x10 board, show short solution and saving on database.
docker-compose exec app python  puzzle_queen.py --full_board --short_board --pieces 10

# Calculate 10 queens and show solutions on 10x10 board, show short solution without save on database.
docker-compose exec app python  puzzle_queen.py --save_db --full_board --short_board --pieces 10

# Get from database the solutions for 10 queens and show on 10x10 board
docker-compose exec app python  puzzle_queen.py --get_db --full_board --pieces 10

Connect to database

For connect to database container

source .env
docker-compose exec db  psql -U $POSTGRES_USER $POSTGRES_DB

Demo:

Queens Puzzle with python example

Queens Puzzle with python - 12x12

Queens Puzzle with python - 13x13