Determine if String Halves Are Alike

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.

Example 1:

Input: s = "book"
Output: true
Explanation: a = "bo" and b = "ok". a has 1 vowel and b has 1 vowel. Therefore, they are alike.

Example 2:

Input: s = "textbook"
Output: false
Explanation: a = "text" and b = "book". a has 1 vowel whereas b has 2. Therefore, they are not alike.
Notice that the vowel o is counted twice.

Example 3:

Input: s = "MerryChristmas"
Output: false

Example 4:

Input: s = "AbCdEfGh"
Output: true

Constraints:

• 2 <= s.length <= 1000

• s.length is even.

• s consists of uppercase and lowercase letters.

Solution:

class Solution {
    public boolean halvesAreAlike(String s) {
        String s1=s.substring(0,s.length()/2);
        String s2=s.substring(s.length()/2,s.length());
        String vowels = "AEIOUaeiou";
        
        int a=0,b=0;
        for(int i=0;i<s1.length();i++)
        {
            if(vowels.indexOf(s1.charAt(i))>=0)
                a++;
            if(vowels.indexOf(s2.charAt(i))>=0)
                b++;
        }
        return a==b;
    }
}