display_triangles.rb

def triangle_up(num, char)
  1.upto(num) { |i| puts char * i }
end

def triangle_down(num, char)
  num.downto(1) { |i| puts char * i }
end

display_triangles_for.rb

## using for loop

def triangle_up(num, char)
  for i in 1..num
    puts char * i
  end
end

def triangle_down(num, char)
  # for loops cant go backwards
  # eg. you can't do `for i in 5..1`
  for i in 0..(num - 1)
    puts char * (num - i)
  end
end

display_triangles_until.rb

## using until loop

def triangle_up(num, char)
  i = 0
  until i > num
    puts char * i
    i += 1
  end
end

def triangle_down(num, char)
  i = num
  until i == 0
    puts char * i
    i -= 1
  end
end

display_triangles_while.rb

## using while loop

def triangle_up(num, char)
  i = 0
  while i <= num
    puts char * i
    i = i + 1 # or i += 1
  end
end

def triangle_down(num, char)
  i = num
  while i > 0
    puts char * i
    i = i - 1 # or i -= 1
  end
end

display_triangles_without_multiply.rb

# without using string multiplication

def triangle_up(num, char)
  1.upto(num) do |i|
    i.times do
      print char
    end
    
    puts
  end
end


def triangle_up(num, char)
  num.downto(1) do |i|
    i.times do
      print char
    end
    
    puts
  end
end