Shortest Driver Distance (Lyft)

shortest_distance.rb

require 'rspec'

module Trip
  def distance(a, b)
    lat_dist = (a[:lat] - b[:lat]).abs
    long_dist = (a[:long] - b[:long]).abs
    Math.sqrt(lat_dist**2 + long_dist**2)
  end
  
  def route_distance(*points)
    legs = []
    points[0...-1].each_with_index do |point, i|
      legs << distance(point, points[i + 1])
    end
    legs.inject(0) {|sum, num| num + sum }
  end
end

# Driver Code
include Trip

@a = {lat: 0, long: 78}
@b = {lat: 6, long: 70}
@c = {lat: 30, long: 63}
@d = {lat: 42, long: 58}

route_a = [@a, @c, @d, @b]
route_b = [@c, @a, @b, @d]

dist_a = route_distance(*route_a)
dist_b = route_distance(*route_b)

p "Driver 1 is driving from #{route_a.join(' to ')} with a total distance of #{dist_a}"
p "Driver 2 is driving from #{route_b.join(' to ')} with a total distance of #{dist_b}"

p "Driver #{dist_a < dist_b ? 1 : 2} has the shorter distance to travel, by #{(dist_a - dist_b).abs} units of distance"

#Tests

describe Trip do
  include Trip
  
  before(:all) do
    @a = {lat: 0, long: 78}
    @b = {lat: 6, long: 70}
    @c = {lat: 30, long: 63}
    @d = {lat: 42, long: 58}
    @legs = [10, 25, 13]
  end
  
  context "distance" do
    it "should return the correct distance" do
      distance(@a, @b).should == @legs[0]
      distance(@b, @c).should == @legs[1]
      distance(@c, @d).should == @legs[2]
    end
  end
  
  context "route_distance" do
    it "should return the total of all legs" do
      route_distance(@a, @b, @c, @d).should == @legs[0] + @legs[1] + @legs[2]
    end
  end
end