gistfile1.rb

def flatten_with_sums(triangle)
  row_index = triangle.length - 2
  while row_index >= 0
    row = triangle[row_index]
    next_row = triangle[row_index + 1]
    row.each_with_index do |value, index|
      row[index] = [value + next_row[index], value + next_row[index + 1]].max
    end
    row_index -= 1
  end
  triangle
end

puts flatten_with_sums(T).first.first