<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) {
        vector<char> vowels;
        string all_vowel = "aeiouAEIOU";
        int left = 0;
        int right = s.size() - 1;
        bool left_vowel = false;
        bool right_vowel = false;
        while(left <= right){
            left_vowel = is_vowel(s[left], all_vowel);
            right_vowel = is_vowel(s[right], all_vowel);
            if (!left_vowel) left++;
            if (!right_vowel) right--;
            if (left_vowel && right_vowel){
                char temp = s[left];
                s[left] = s[right];
                s[right] = temp;
                left++;
                right--;
            }
        }
        return s;
    }
    bool is_vowel(char s, string all_vowels){
        bool flag = false;
        for (int i = 0; i < all_vowels.size(); i++){
            if (all_vowels[i] == s){
                flag = true;
                break;
            }
        }
        return flag;
    }

};
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