# 1704. Determine if String Halves Are Alike

### Description

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`.

### Constraints

* `2 <= s.length <= 1000`
* `s.length` is even.
* `s` consists of **uppercase and lowercase** letters.

### Approach

### Links

* GeeksforGeeks
* [Leetcode](https://leetcode.com/problems/determine-if-string-halves-are-alike/)
* ProgramCreek
* YouTube

### **Examples**

{% tabs %}
{% tab title="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.
{% endtab %}

{% tab title="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.
{% endtab %}

{% tab title="Example 3" %}
**Input:** s = "MerryChristmas"

**Output:** false
{% endtab %}

{% tab title="Example 4" %}
**Input:** s = "AbCdEfGh"

**Output:** true
{% endtab %}
{% endtabs %}

### **Solutions**

{% tabs %}
{% tab title="Solution 1" %}

```java
/**
 * Time complexity : O(N), since we need to iterate substring a and b.
 * Space complexity : O(1), since we do not need extra space. 
 *    Here we do not take the input s into consideration.
 */

class Solution {
    public boolean halvesAreAlike(String s) {
        int vowelsDiff = 0;
        
        for(int i = 0, j = s.length()-1; i < j; i++, j--) {
            if(isVowel(s.charAt(i))) {
                vowelsDiff++;
            }
            if(isVowel(s.charAt(j))) {
                vowelsDiff--;
            }
        }
        
        return vowelsDiff == 0;
    }
    
    private boolean isVowel(char ch) {
        switch(ch) {
            case 'a':
            case 'e':
            case 'i':
            case 'o':
            case 'u':
            case 'A':
            case 'E':
            case 'I':
            case 'O':
            case 'U': return true;
        }
        return false;
    }
}
```

{% endtab %}
{% endtabs %}

### **Follow up**

*


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://code-snippets.hbamithkumara.com/leetcode/problems/1701-1800/determine-if-string-halves-are-alike.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.