Array that alphabetizes and alternates between all

问题:

I need to get the user to input five words, which I believe I have. Then the program needs to spit the words in alphabetical order with every other word being in all-caps, starting with the first word, and the remaining words being in all lowercase.

I'm eventually going to have switch the loop to 500 words, and it's only the number in the loop that I need to change. How do I get this to work?

Here's what I have so far:

words = []

5.times do
  puts "Please enter a word"
  words << gets.chomp
end

puts words.sort.odd.upcase

回答1:

with_index can help you with the every other word problem:

words = %w(hello world this is test)
# => ["hello", "world", "this", "is", "test"]
words.map(&:downcase).sort.map.with_index {|word, index| index.odd? ? word : word.upcase}
# => ["HELLO", "is", "TEST", "this", "WORLD"]

回答2:

Here are two ways that don't use indices.

arr = %w|the quicK brown dog jumpEd over the lazy fox|
  #=> ["the", "quicK", "brown", "dog", "jumpEd", "over", "the", "lazy", "fox"]

Note:

arr.sort
  #=> ["brown", "dog", "fox", "jumpEd", "lazy", "over", "quicK", "the", "the"] 

#1

e = [:UC, :LC].cycle
arr.sort.map { |w| (e.next == :UC) ? w.upcase : w.downcase }
  # => ["BROWN", "dog", "FOX", "jumped", "LAZY", "over", "QUICK", "the", "THE"]

#2

arr.sort.each_slice(2).flat_map { |u,v| v ? [u.upcase, v.downcase] : [u.upcase] }
  # => ["BROWN", "dog", "FOX", "jumped", "LAZY", "over", "QUICK", "the", "THE"]  

回答3:

If I understand well (but the question is not so clear) you want to sort and then put one word out of two in uppercase and the other in lowercase:

words.sort.each_with_index.map{|w,i| i.odd? ? w.upcase : w.downcase }

Test:

words=%w( orange banana apple melon)

Result:

["APPLE", "banana", "MELON", "orange"]

回答4:

Just out of curiosity:

arr = %w(orange apple lemon melon lime)
a1, a2 = arr.sort.partition.with_index { |_, i| i.even? }
a1.map(&:downcase).zip(a2.map &:upcase).flatten.compact

回答5:

I'd use:

user_input = %w(the quick red fox jumped)
uc_flag = true
output = []
user_input.sort.each { |w| 
  output << if uc_flag
              w.upcase
            else
              w.downcase
            end
  uc_flag = !uc_flag
}
output # => ["FOX", "jumped", "QUICK", "red", "THE"]

It's old-school but is extremely fast as it only makes one pass through the array.

It can be written a bit more tersely using:

output << (uc_flag ? w.upcase : w.downcase)

but ternary statements are generally considered to be undesirable.

If the user is allowed to enter mixed-case words, use:

sort_by(&:downcase) 

instead of sort.