Description: https://leetcode.com/problems/detect-capital/

Solution:

def detect_capital_use(word)
    (word == word.downcase) ||
    (word == word.upcase) ||
    (word == word.downcase.capitalize)
end

Explanation:

1- Check if the word is the same after converting it all to downcase.

1.2- Check if the word is the same after converting it all to upcase.

1.3- Check if the word is the same after converting it all to downcase and then converting the first character to upcase.