validating-valleys.rb

# https://www.hackerrank.com/challenges/counting-valleys/problem?h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=warmup

# samples
path = "UDDDUDUU"
path = "UUUUUUUU"
path = "DDDDDDDD"
path = "UUUDDD"
path = "UUUUDD"

# ruby 2.7+
def validatingValleys(path)
  path_splitted = path.split("")
  values = path_splitted.tally.values
  return 1 if path_splitted.count.even? && values.count > 1 && values.uniq.size == 1
  0
end

# past versions
def validatingValleys(path)
  path_splitted = path.split("")
  values = path_splitted.group_by(&:itself).transform_values{|v| v.size}.values
  return 1 if path_splitted.count.even? && values.count > 1 && values.uniq.size == 1
  0
end

def countingValleys(steps, path)
    position = 0
    valleys = 0

    path.each_char do |step|
      old_position = position
      position += 1 if step == "U"
      position -= 1 if step == "D"

      valleys += 1 if position.zero? && old_position.negative?
    end

    valleys
end