# Sample answers for Lab Exam 2 (Spring 2012)

def f1()
  # Flag of Denmark
  Canvas.init(450,350,"f1")
  Canvas::Rectangle.new(0,0,449,349,:fill=>"red")
  Canvas::Rectangle.new(150,0,199,349,:fill=>"white",:outline=>"white")
  Canvas::Rectangle.new(0,150,449,199,:fill=>"white",:outline=>"white")
end

def f2(n)
  # Compute 2**n recursively
  if n == 0 then
    return 1
  else
    return 2 * f2(n-1)
  end
end

def f3(numrows,numcols)
  # Array of random values between 2 and 7
  matrix = Array.new(numrows)
  for i in 0..numrows-1
    matrix[i] = Array.new(numcols)
    for j in 0..numcols-1
      matrix[i][j] = 2 + rand(6)
    end
  end
  return matrix
end

def f4a(matrix)
  # Count the odd elements using each
  count = 0
  matrix.each {|row|
    row.each{|element|
      count += 1 if element.odd?
    }
  }
  return count
end

def f4b(matrix)
  # Count the odd elements using for loops
  count = 0
  for i in 0..matrix.length-1 do
    for j in 0..matrix[i].length-1 do
      if matrix[i][j].odd? then
	count = count + 1
      end
    end
  end
  return count
end