Dev Share Problem

brief.txt

Take https://gist.github.com/ajesler/5c06c3bc5a9856f55472c617403a83d8 and solve the problem. Have a little fun with the solution, see what inefficient, ridiculous solutions you can come up with, push the bounds of your ruby knowledge a little. What constraints can you apply on how you solve it? 
Full problem description at https://www.hackerrank.com/challenges/counting-valleys/problem?isFullScreen=true


Ideas: Can you do it in a single enumerable chain, can you write a program that generates the solver with meta programming, can you do it without using the letter e. 

30m of problem solving in pairs, then 3m each to discuss what you tried to do, and what the highlights of your solution, working or otherwise. Don't worry if it doesn't work, its more about the journey and what you can learn. 

dev_share_problem.rb

# frozen_string_literal: true
# This is the Counting Valleys problem from hackerrank.com
# https://www.hackerrank.com/challenges/counting-valleys/problem?isFullScreen=true

# Run the solver with the input after __END__
# $ ruby counting_valleys.rb
#
# Run the solver using a file as input
# $ ruby counting_valleys.rb test_input.txt
#
# Run solver specs with
# $ ruby counting_valleys.rb --specs

require 'bundler/inline'

# Uncomment this block to install byebug
# gemfile true do
#   source 'https://rubygems.org'

#   gem 'test-unit'

#   # Useful for debugging
#   gem 'byebug', platforms: [:mri, :mingw, :x64_mingw]
#   gem 'pry-byebug'
# end

require 'timeout'
require 'test/unit'
Test::Unit::AutoRunner.need_auto_run = false

class ValleyCounter
  def initialize(steps, path)
    @steps = steps
    @path = path
  end

  def count
    1
  end
end

class ValleyCounterSpec < Test::Unit::TestCase
  def expect_valley_count(expected_count, steps:, path:)
    valley_count = ValleyCounter.new(steps, path).count
    assert_equal expected_count, valley_count
  end

  def test_one
    expect_valley_count(1, steps: 8, path: 'UDDDUDUU')
  end

  def test_two
    expect_valley_count(2, steps: 12, path: 'DDUUDDUDUUUD')
  end

  def test_three
    steps = 100
    path = 'DDUUDDDUDUUDUDDDUUDDUDDDUDDDUDUUDDUUDDDUDDDUDDDUUUDUDDDUDUDUDUUDDUDUDUDUDUUUUDDUDDUUDUUDUUDUUUUUUUUU'

    expect_valley_count(2, steps: steps, path: path)
  end
end

if $PROGRAM_NAME == __FILE__
  first_argument = ARGV.shift

  if first_argument == '--specs'
    # Run the specs
    Test::Unit::AutoRunner.need_auto_run = true
  else
    data_source = first_argument.nil? ? DATA.read : File.read(first_argument)
    raw_steps, raw_path = data_source.split(/\r?\n/, 2)

    steps = raw_steps.to_i
    path = raw_path.strip

    if steps != path.delete('_').length
      raise("path mismatch! Expected path of #{steps}, got #{path} which is #{path.delete('_').length}")
    end

    valley_counter = ValleyCounter.new(steps, path)
    puts valley_counter.count
  end
end

__END__
8
UDDDUDUU

test.txt

1000000