<p>Given a string <code>s</code>, reverse only all the vowels in the string and return it.</p>

<p>The vowels are <code>&#39;a&#39;</code>, <code>&#39;e&#39;</code>, <code>&#39;i&#39;</code>, <code>&#39;o&#39;</code>, and <code>&#39;u&#39;</code>, and they can appear in both lower and upper cases, more than once.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = &quot;IceCreAm&quot;</span></p>

<p><strong>Output:</strong> <span class="example-io">&quot;AceCreIm&quot;</span></p>

<p><strong>Explanation:</strong></p>

<p>The vowels in <code>s</code> are <code>[&#39;I&#39;, &#39;e&#39;, &#39;e&#39;, &#39;A&#39;]</code>. On reversing the vowels, s becomes <code>&quot;AceCreIm&quot;</code>.</p>
</div>

<p><strong class="example">Example 2:</strong></p>

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = &quot;leetcode&quot;</span></p>

<p><strong>Output:</strong> <span class="example-io">&quot;leotcede&quot;</span></p>
</div>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 3 * 10<sup>5</sup></code></li>
	<li><code>s</code> consist of <strong>printable ASCII</strong> characters.</li>
</ul>

class Solution {
public:
    string reverseVowels(string s) {
        ios_base::sync_with_stdio(false);
        cin.tie(0);
        cout.tie(0);
        int i = 0;
        int j = s.size() - 1;

        // Function to check if a character is a vowel
        auto isVowel = [](char c) {
            c = tolower(c);
            return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
        };

        // Two-pointer approach to reverse the vowels
        while (i < j) {
            // Find the next vowel from the start
            while (i < j && !isVowel(s[i])) {
                i++;
            }
            // Find the next vowel from the end
            while (i < j && !isVowel(s[j])) {
                j--;
            }

            // Swap the vowels
            if (i < j) {
                swap(s[i], s[j]);
                i++;
                j--;
            }
        }

        return s; // Return the modified string
    }
};

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