string halves comparison by counting number of vowels in each half
You are given a string s of even length. Split this string into two halves of equal lengths, and let a be the first half
and b be the second half.
Two strings are alike if they have the same number of vowels ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O',
'U'). Notice that s contains uppercase and lowercase letters.
Return true if a and b are alike. Otherwise, return false.
This is a question from leetcode.com