# 1704. Determine if String Halves Are Alike

Easy
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.
Constraints:
• `2 <= s.length <= 1000`
• `s.length` is even.
• `s` consists of uppercase and lowercase letters.

### 解題

log(n)
Runtime: 0 ms, faster than 100.00%
Memory Usage: 2.1 MB, less than 86.27%
func halvesAreAlike(s string) bool {
count1 := 0
count2 := 0
for i:=0; i<len(s)/2; i++ {
if isVowel(s[i]) { count1++ }
}
for i:=len(s)/2; i<len(s); i++ {
if isVowel(s[i]) { count2++ }
}
return count1 == count2
}
func isVowel(char byte) bool {
if char >= 'A' && char <= 'Z' {
char += 32
}
return char == 'e' || char == 'u' || char == 'o' || char == 'a' || char == 'i'
}