7/15/20 problems Hashes

Question 1

Write a method frequent_letters that takes in a string and returns an array containing the characters that appeared more than twice in the string.

Answer 1

def frequent_letters(string)
  freq_hash = Hash.new(0)

freq_letters = []

alphabet = (“a”..”z”)

  string.each_char do |char|
    if alphabet.include?(char)
      freq_hash[char] += 1
    end
  end

  freq_hash.each do |k, v|
    if v > 2
      freq_letters << k
    end
  end
  return freq_letters
  # return freq_hash
end

p frequent_letters('mississippi    is best!!!!!') #=> ["i", "s"]
p frequent_letters('bootcamp') #=> []

Question 2

anagram returns boolean representing whether the letters in word1 can be rearranged to form word2

Answer 2

def anagram?(word1, word2)
#do each word contain the same amount of each letter
  hash1 = Hash.new(0)
  hash2 = Hash.new(0)

alphabet = (“a”..”z”)

  word1.each_char do |char|
    if alphabet.include?(char)
      hash1[char] += 1
    end
  end
  word2.each_char do |char|
    if alphabet.include?(char)
      hash2[char] += 1
    end
  end

if hash1 == hash2
#comparing keys is most common
end
p anagram?(“teacher”, “cheater”) # => true
p anagram?(“desert”, “dessert”) # => false

Question 3

takes integer and converts to roman numeral string

Answer 3

def int_to_roman(num)
   roman_hash = {
     "M" => 1000,
     "CM" => 900,
     "D" => 500,
     "CD" => 400,
     "C" => 100,
     "XC" => 90,
     "L" => 50,
     "XL" => 40,
     "X" => 10,
     "IX" => 9,
     "V" => 5,
     "IV" => 4,
     "I" => 1
   }
 end
 puts int_to_roman(5) #=> "V"
puts int_to_roman(1764) #=> "MDCCLXIV"
puts int_to_roman(999) #=> "CMXCIX"