Quick and simple interview coding exercises

arrays.rb

# When given an array with a single duplicate number,
# it returns that number.
def find_duplicate_number(arr)
  arr
end

puts '# find_duplicate_number:'
puts find_duplicate_number([5,3,7,2,3,1]) == 3



# When given an array with any number of duplicate numbers,
# it returns an array of all those numbers (each number only once).
def find_duplicate_numbers(arr)
  arr
end

puts '# find_duplicate_numbers:'
nums = find_duplicate_numbers([5,3,7,2,7,7,3,1])
puts nums.sort == [3,7]



# When given an array with any number of duplicate numbers,
# it returns an array without any duplicates.
def remove_duplicate_numbers(arr)
  arr
end

puts '# remove_duplicate_numbers:'
nums = remove_duplicate_numbers([5,3,7,2,7,3,1])
puts nums.sort == [1,2,3,5,7]



# When given an array of numbers, it reverses it.
def reverse(arr)
  arr
end

puts '# reverse:'
puts reverse([1,2,3,4,5]) == [5,4,3,2,1]



# When given an array with numbers,
# it returns the lowest and highest numbers (in a two dimensional array)
# e.g. [2,3,1,3] => [1, 3]
def lowest_and_highest(arr)
  [0,0]
end

puts '# lowest_and_highest:'
puts lowest_and_highest([2,3,1,3]) == [1,3]



# When given an array of numbers (arr) and a number (n),
# it returns all pairs in arr that sum up to n.
def pairs_with_sum(arr, n)
  []
end

puts '# pairs_with_sum:'
puts pairs_with_sum([1,2,3,4,5,6], 8) == [[2,6], [3,5]]

strings.rb

# When given two strings,
# it returns true when they are anagrams of each other, false otherwise.
def anagrams?(str1, str2)

end

puts '# anagrams?:'
puts anagrams?('abcd', 'bdca') == true
puts anagrams?('abcd', 'badca') == false



# When given a string, it reverses it using recursion
def recursive_reverse(str)

end

puts '# recursive_reverse:'
puts recursive_reverse('abcdef') == 'fedcba'



# When given a string with multiple words in it,
# it returns a string with each individual word reversed.
# e.g. 'ab cd' => 'ba dc'
def reverse_words(str)

end

puts '# reverse_words:'
puts reverse_words('one two three') == 'eno owt eerht'



# When given a string,
# it returns true if it is a palindrome, false otherwise.
def palindrome?(str)

end

puts '# palindrome?:'
puts palindrome?('abcbca') == false
puts palindrome?('abcdcba') == true



# When given two strings,
# it returns true when they are rotation of the same string.
def rotated_equals?(str1, str2)

end

puts '# rotated_equals?:'
puts rotated_equals?('abcdef', 'cdefab') == true
puts rotated_equals?('abcdef', 'bacdef') == false
puts rotated_equals?('abcdef', 'cdefxab') == false



# When given a string,
# it returns the vowel count and consonant count (2 element array)
def counts(str)
  [0, 0]
end

puts '# counts:'
puts counts('abCdEf') == [2, 4]