KevinSia

# Implement an iterative version of the factorial function
def factorial_iterative(n)
  return n if n <= 1
  total = 1
  n.downto(1) { |i| total *= i }
  return total
end

# def factorial_iterative(n)
#   return n if n <= 1

KevinSia

# Place your solutions here
# Implement a method named binary_search
def binary_search(target, arr)
  s = 0
  e = arr.length - 1
  until s < e
    m = (s + e) / 2
    # found target
    if target == arr[m]
      return m

KevinSia

def linear_search(target, arr)
  for i in 0...arr.length
    return i if target == arr[i]
  end
  return nil
end

def global_linear_search(target, arr)
  indices = []
  for i in 0...arr.length

KevinSia

def prime_factors(num)
  return [num] if num <= 1
  
  result = []
  until num == 1
    for i in (2..num)
      if num % i == 0
        result << i
        num /= i
        break

KevinSia

# TODO: Refactor for elegance
def shout_backwards(string)
  # before:
  # all_caps  = string.upcase
  # backwards = all_caps.reverse
  # result    = backwards + "!!!!"

  # return result
  string.upcase.reverse + "!!!!"
end

KevinSia

# Fill in the methods below with your solution.
# Do not change the method names

# Iteration 1: Converting one word to Pig Latin

def convert_word_to_pig_latin(word)
  if word[0].downcase == 'a' || word[0].downcase == 'e' || word[0].downcase == 'i' || word[0].downcase == 'o' || word[0].downcase == 'u'
    word
  else
    str_front = ''

KevinSia

# Determine whether a string contains a Social Security number.
def has_ssn?(string)
  !!string.match(/(\d{3})-(\d{2})-(\d{4})/)
end

puts "has_ssn? returns true if it has what looks like a SSN"
puts has_ssn?("please don't share this: 234-60-1422") == true

puts "has_ssn? returns false if it doesn't have a SSN"

KevinSia

# Fisher-Yates shuffle
# the wiki shows two examples
# https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle

# pencil-and-paper method
# 1. Duplicate the array and shuffle the duplicate instead (we call the duplicate `input_array`)
# 2. Generate a random number between 0 and (length of the array - 1) (we call the number `random_position`)
# 3. Take an element at position `random_position` in the `input_array`, and put into another array
# 4. Repeat 2-3 until `input_array` has nothing left

KevinSia

# Your code here to sort the array
def dictionary_sort(array)
  return if array.length <= 1
  array.sort { |word1, word2| word1.downcase <=> word2.downcase }
end

# writing `array.sort` is equivalent to writing `array.sort { |i, j| i <=> j }`
# .sort decides which item should be in the front by doing `<=> on each pair of items
# if the block gives -1, i goes to the front and j goes to the back
# if the block gives 1, j goes to the front and i goes to the back

KevinSia

def canonical(word)
  word.downcase.chars.sort
end

def is_anagram?(word1, word2)
  canonical(word1) == canonical(word2)
end

puts "One word"
word1 = gets.chomp