stupid.rb

# Write a method that takes a string in and returns true if the letter
# "z" appears within three letters **after** an "a". You may assume
# that the string contains only lowercase letters.
#
# Difficulty: medium.

# may want to do max+1 as base-zero can be confusing
def x_after_y?(str, char1, char2, max)
  range = Range.new(1, max)
  str.slice!(str.chars.index(char1))
  if str.length > 0
    range.find {|n| true if str.chars.at(n) == char2}
  end
end

---
[7] pry(main)> x_after_y?('asdz', 'a', 'z', 3)
=> 2