InterviewBit Problems   Vowels : Unsolved

About the Vowels : Unsolved category (1)
What is the expected time complexity for this question? (1)
I have solved this problem but it is exceeding time limit (1)
Time limit exceeded in bigger integer number (1)
Recursion error in python (3)
DOUBT - Regarding Answer (2)
Right answer when running as custom input, Wrong answer on submitting (2)
Overflow of ans (6)