There are many possible solutions to this problem. The simplest is to group the characters into two categories, vowels (aiueo) and consonants (knhfmr). Then, iterate through the string from left to right. If the current character is a vowel, we move one index forwards. Otherwise, if it's a consonant, we check that the next character is a vowel and move two indices forwards if it is. The word is then valid if and only if we reach the end of the string. Of course, careful attention should be paid to the details of handling the fu case.

Time Complexity: ~\mathcal{O}(N)~ where ~N~ is the length of the string.