Ordered Vowels

January 31, 2017

Today’s exercise is to write a program that finds all the words in a dictionary in which all the vowels in the word appear in ascending order. It is not necessary that all five vowels appear in the word, and vowels may be doubled. For instance, afoot passes because the three vowels, a, o and o appear in non-decreasing order.

An easy way to solve this problem uses regular expressions:

$ grep '^[^aeiou]*a*[^aeiou]*e*[^aeiou]*i*[^aeiou]*o*[^aeiou]*u*[^aeiou]*$' /etc/dict/words

Since that is so easy, you must write a program that does not use regular expressions.

Your task is to write a program that finds words with ordered vowels. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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