1704. Determine if String Halves Are Alike

#### QUESTION:

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.
``````

#### EXPLANATION:

easy的题目， 一个for循环进行判断即可。

#### SOLUTION:

``````class Solution {
func halvesAreAlike(_ s: String) -> Bool {
var vowels:[String] = ["a", "e", "i", "o", "u", "A", "E", "I", "O", "U"]
var countA:Int = 0
var countB:Int = 0
let arr = Array(s)
for index in 0...arr.count-1 {
if vowels.contains(String(arr[index])) {
if index + 1 <= (arr.count / 2) {
countA += 1
} else {
countB += 1
}
}
}
return countA == countB
}
}
``````