andersonberg / coindeterminer

Coin Determiner

This site was built with Django web framework (version 1.8.2) and Python (version 3.4). The database used to store objects was postgresql.

To use this project follow these steps:

1. Install Postgresql
2. Install Django
3. Install additional dependencies
4. Create the database
5. Run the project

Install Postgres

The installation depends on which operational system you are using. Please, refer to https://wiki.postgresql.org/wiki/Detailed_installation_guides for further instructions.

Installing Django

To install Django, run the following command:

$ pip install django

Installation of Dependencies

Depending on where you are installing dependencies:

In development:

$ pip install -r requirements/local.txt

For production:

$ pip install -r requirements.txt

Create the database

This step probably is the more complex (but still very simple), you need to open the psql and create a role and a database:

CREATE USER postgres LOGIN CREATEDB PASSWORD 'postgres';
CREATE DATABASE coindeterminerdb OWNER postgres;

And to conclude, migrate the database and run the project:

#path: coindeterminer_project/coindeterminer_project/
$ python manage.py makemigrations
$ python manage.py migrate

Run the project

To run the project it's simple, just run the following command:

$ python manage.py runserver

The site will be available via browser at http://localhost:8000/

Populate database

The only objects stored in database are the coins. Accessing the admin area you can add the available coins to run the project.

A coin has only one attribute, its value.

The Views

We used Class Based Views from Django. We choose this before FBV, because is more suitable for our needs and CBV easy the way we handle form data.

The Solution

To solve the Coin Determiner problem, we take different solutions by starting with each coin available. Then the minimal solution is chosen.

Each solution is built in the following way:

1. The quotient between the number provided and the first coin (in a sorted list) indicates de amount of a certain coin we must use.
2. The rest indicates how much is required to reach the total amount.
3. The rest is user do get a new quotient, this time using the next coin available in the sorted list.
4. The quotients are added and this sum is the answer.