> For the complete documentation index, see [llms.txt](https://joshualbarb.gitbook.io/leetcode-problems/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://joshualbarb.gitbook.io/leetcode-problems/strings/string-simulation/reverse-vowels-of-a-string.md).

# Reverse Vowels of a String

String Simulation

## Problem

Write a function that takes a string as input and reverse only the vowels of a string.

{% hint style="info" %}
For example:

```
Input: "hello"
Output: "holle"
```

```
Input: "leetcode"
Output: "leotcede"
```

{% endhint %}

### Thought Process

* You can use 2 pointer approach for this problem
* We have to convert the string to a list in order to reassign elements

## Solution

```
class Solution:
    def reverseVowels(self, s: str) -> str:
        
        s = list(s) 
    # converting string to list 
    # because strings do not support 
    # item assignment 
        vowels = 'aeiouAEIOU'
        i = 0
        j = len(s)-1
        
        while i < j:
            while i < j and s[i] not in vowels: #finding the first vowel we come across
                i+=1
            while i < j and s[j] not in vowels: #finding the first vowel we come across
                j-=1
            
            s[i], s[j] = s[j], s[i]
            i+=1
            j-=1
        return "".join(s)
            
```

## Time Complexity

* **Time:** O(n) since we are using the two pointer approach and going linearly. Also, when we look up to see if the element is a vowel, it will take O(10) which is just O(1)

* **Space**: O(1)