8 kyu - Thinkful - Logic Drills: Traffic light.md

Task

You're writing code to control your town's traffic lights. You need a function to handle each change from green, to yellow, to red, and then to green again.

Complete the function that takes a string as an argument representing the current state of the light and returns a string representing the state the light should change to.

For example, update_light('green') should return 'yellow'.

My solution

def update_light(current)
  case
  when current == "green"
  return "yellow"
  when current == "yellow"
  return "red"
  when current == "red"
  return "green"
  end
end

Better solution

def update_light(current)
  {"green" => "yellow", "yellow" => "red", "red" => "green"}[current]
end

Better solution 2

def update_light(current)
  {
    'green' => 'yellow',
    'yellow'=> 'red',
    'red'   => 'green'
  }.fetch(current)
end

Explanation

This an example of a case when statement. It just builds on when the light is X then change it to Y