validBraces.rb

def validBraces(string)
  opening_character = ['(', '[', '{']
  closing_character = [')', ']', '}']

  string.split('').each_with_object([]) do |character, stack|
    if opening_character.include?(character)
      stack << character
    else
      return false if closing_character.index(character) != opening_character.index(stack.pop)
    end
  end

  true
end

puts validBraces( "(){}[]" )
puts validBraces( "(}" )
puts validBraces( "[(])" )
puts validBraces( "([{}])" )