Week 1 Practice problems

Question 1

### implement your own include version of string.include?
# easy mode: you can assume search_term is one character
# challenge mode: search for more than one character
# my_include("chris","is") -> true

Answer 1

# def my_include?(string, search_term)
# end
# p my_include?("avatar aang","a") # true
# p my_include?("Fullmetal Alchemist","f") # false
# p my_include?("avatar aang","tar") # true
# p my_include?("teacher","cheat") # false
# p my_include?("manslaughter","laughter") # true

Question 2

# given an array of integers
# return an array of the squares of those integers

Answer 2

def square_array(arr)
  # thats why you're here!
  squared = []
  i = 0
  while i < arr.length
    squared << arr[i] * arr[i]
    i += 1
  end
  return squared
end
# p square_array([1, 2, 3, 4]) # [1, 4, 9, 16]
# p square_array([1, 3, 5, 9]) # [1, 9, 25, 81]

Question 3

# given a string
# return a string of ONLY the words which are length 5 or greater
# (hint: how can we break a string up into individual words?)

Answer 3

def big_words(str)
big_words_arr = []
# split initial string into individual words
splitted_str = str.split(“ “)
i = 0
while i < splitted_str.length
# check if the word is length 5 or greater
if splitted_str[i].length >= 5
big_words_arr &laquo_space;splitted_str[i]
end
i += 1
end
return big_words_arr.join(“ “)
end
p big_words(“the quick brown fox jumped over the lazy dog”)
# => “quick brown jumped”
p big_words(“kevin is an absolute unit!!!!! The sheer size of this madman!”)
# => “kevin absolute unit!!!!! sheer madman!”

Question 4

# given an array, return every unique el in the array (in order of appearance)
# cannot use .uniq method

Answer 4

# def unique_items(arr)
# end
# unique_items([0, 2, 0, 0, "dog", 2]) -> [0, 2, "dog"]

Question 5

# given an array of numbers
# return the SECOND biggest number
  # without using the sort method

Answer 5

# def second_largest_number(arr)
  # without using the sort method
# end
# p second_largest_number([6,7,8,9,10,1,2,3,4,5]) # 9
# p second_largest_number([5,4,5,4]) # 5
# p second_largest_number([1,2,2,3]) # 2
# p second_largest_number([19]) # nil

Question 6

# A magic number is a number whose digits, when added together, sum
# to 7, e.g., 34. Define a method that checks if a number is a magic number.

Answer 6

# def magic_number?(num)
# end
# p magic_number?(7) # true
# p magic_number?(4201) # true
# p magic_number?(82) # false

Question 7

# magic_numbers method return an array of the first n magic numbers
# magic_numbers(3) => [7, 16, 25]

Answer 7

# def magic_numbers(n)
# end
# p magic_numbers(3)
# p magic_numbers(50)

Question 8

# given 2 sorted arrays
# merge the 2 arrays into a single, sorted array
# no .sort
# (hint: how can we take advantage of the fact that our arrays come pre-sorted?)
# (hint: the smallest number in our merged array started at which position?)

Answer 8

# def merge_sorted_arrays(arr1,arr2)
# end
# p merge_sorted_arrays([1,2,4],[3,6,10,11]) # [1, 2, 3, 4, 6, 10, 11]
# p merge_sorted_arrays([1,2,3],[4,5]) # [1, 2, 3, 4, 5]
# p merge_sorted_arrays([1,1,2,6],[1,2,2]) # [1, 1, 2, 2, 2, 6]

Question 9

### Titleize
#
# Write a method that capitalizes each word in a string like a book title.
# Do not capitalize the words: 'a', 'and', 'of', 'over' or 'the'.

Answer 9

# def titleize(title)
# end
# puts titleize("basketball") == "Basketball"
# puts titleize("stephen curry") == "Stephen Curry"
# puts titleize("war and peace") == "War and Peace"
# puts titleize("the bridge OVER the river kwai") == "The Bridge over the River Kwai"