AtCoder AGC #003 [Ruby]

agc003-a.rb

# AC
s = gets.chomp
if (s.include?("N") && s.include?("S") && !s.include?("E") && !s.include?("W")) || (!s.include?("N") && !s.include?("S") && s.include?("E") && s.include?("W")) || (s.include?("N") && s.include?("S") && s.include?("E") && s.include?("W")) then
  puts "Yes"
else
  puts "No"
end

agc003-b.rb

# AC
n = gets.chomp.to_i
a = []
n.times do
  a << gets.chomp.to_i
end
ans = 0
n.times do |i|
  ans += a[i] / 2
  if a[i] % 2 == 1  && i != n - 1 then
    if a[i + 1] != 0 then
      ans += 1
      a[i + 1] -= 1
    end
  end
end
puts ans

agc003-c.rb

# AC
n = gets.chomp.to_i
a = Hash.new
n.times do |i|
  x = gets.chomp.to_i
  a[x] = i % 2
end

ans = 0
a.keys.sort.each_with_index do |x, i|
  ans += 1 if a[x] != i % 2
end
puts ans / 2