Find the last non-repeating character in a given string.

non_repeat.rb

def non_repeat(str)
  counts = Hash.new(0)
  
  str.each_char { |char| counts[char] += 1 }
  str.reverse.each_char do |char|
    return char if counts[char] == 1
  end
  
  ""
end

puts non_repeat('candy canes do taste yummy')