We first need a Ruby version manager, we'll use rbenv in this guide. To install rbenv, follow all 5 steps from here: https://github.com/rbenv/rbenv#basic-github-checkout.
Now that we have rbenv and the ruby-build plugin installed, we can start installing Ruby.
| def self.within_range(range_km, lat, lng) | |
| if lat.present? && lng.present? | |
| joins(location: :point) | |
| .where( | |
| "ST_DWithin(Geography(ST_MakePoint(longitude, latitude)), | |
| Geography(ST_MakePoint(#{lng}, #{lat})), | |
| #{(range_km * 1000).to_i})" | |
| ) | |
| else | |
| none |
| def calc(arr) | |
| arr[0] + (13.0 * arr[1] / arr[2]) + arr[3] + (12 * arr[4]) - arr[5] + (arr[6].to_f * arr[7] / arr[8]) | |
| end | |
| def solutions | |
| [1,2,3,4,5,6,7,8,9].permutation.to_a.keep_if { |p| calc(p) == 87.0 } | |
| end |
Ruby on Rails depends on the Ruby programming language (doh), so we need to install that first. Follow the Ruby Setup guide to install a local version of Ruby.
Install the latest version of Rails
