Code Festival 2017 Qual A

cf2017-quala-a.rb

s = gets.chomp
if s[0..3] == "YAKI" then
  puts "Yes"
else
  puts "No"
end

cf2017-quala-b.rb

n, m, k = gets.chomp.split(" ").map(&:to_i)
black = []
(0..n).each do |i|
  (0..m).each do |j|
    cnt = i * m + j * n - i * j * 2
    black << cnt
  end
end
if black.include?(k) then
  puts "Yes"
else
  puts "No"
end

• C
• D