Hi,
I am new to programming and following Chris Pines book. There is an exercise in the book to write a method similar to .sort that will arrange an array of string in alphabetical order. I will paste the exercise:
OK. So we want to sort an array of words, and we know how to find out which of two words comes first in the dictionary (using <). What strikes me as probably the easiest way to do this is to keep two more lists around: one will be our list of already-sorted words, and the other will be our list of still-unsorted words. We’ll take our list of words, find the “smallest” word (that is, the word that would come first in the dictionary), and stick it at the end of the already-sorted list. All of the other words go into the still-unsorted list. Then you do the same thing again but using the still-unsorted list instead of your original list: find the smallest word, move it to the sorted list, and move the rest to the unsorted list. Keep going until your still-unsorted list is empty.
I think I covered the first bit of the exercise but when I try to repeat my method recursively it fails. Would you be please so kind to take a look at my code and tell me what am I doing wrong?
puts 'Please enter a list of words you would like to arrange' puts 'in alphabetical order:'
list_of_words = input = 'empty'
while input != '' input = gets.chomp if input != '' list_of_words.push input end end
def arrange some_array recursive_arrange some_array, end
def recursive_arrange unsorted_array, sorted_array
# Initializing the array "still_unsorted_array"
still_unsorted_array =
# Finding the smallest word on the array "list_of_words"
smallest = unsorted_array [0]
unsorted_array.each do |word| if smallest > word smallest = word end end
# Adding the smallest word from the array of "unsorted words" to the array of "sorted_words"
sorted_array.push smallest
# Adding the words from the array of "unsorted_array" to the array of "still_unsorted_array" # with the exception of the content of variable "smallest"
bigger = 'empty'
unsorted_array.each do |word| if word != smallest bigger = word still_unsorted_array.push bigger end end
# Clearing the array of "unsorted_array" so it can be re-used
unsorted_array = # Adding the smallest word from the array of "still_unsorted words" to the array of "sorted_words"
smallest = still_unsorted_array [0] still_unsorted_array.each do |word| if smallest > word smallest = word end end
# Adding the smallest word from the array of "still_unsorted words" to the array of "sorted_words"
sorted_array.push smallest
# Adding the remaining words from the array "still_unsorted_words" to the array of # "unsorted_words"
still_unsorted_array.each do |word| if word != smallest bigger = word unsorted_array.push bigger end end
# This is the bit I tried to call the method recursively.
if unsorted_array == unsorted_array = puts sorted_array else recursive_arrange unsorted_array, sorted_array end
puts 'unsorted array:' puts unsorted_array puts 'still unsorted array:' puts still_unsorted_array puts 'sorted array:' puts sorted_array
end
arrange list_of_words
