AtCoder ARC #003

arc003-a-gpa.rb

n = gets.chomp.to_f
grades = gets.chomp.split("")

gpa = 0
grades.each do |g|
  case g
  when "A"
    gpa += 4
  when "B"
    gpa += 3
  when "C"
    gpa += 2
  when "D"
    gpa += 1
  end
end
puts gpa / n

arc003-b-reverse-dict.rb

# [B: さかさま辞書 - AtCoder Regular Contest 003 | AtCoder](http://arc003.contest.atcoder.jp/tasks/arc003_2)
n = gets.chomp.to_i
words = []
n.times do
  words << gets.chomp.reverse
end
words.sort.each do |w|
  puts w.reverse
end