🌱 Keegan's Digital Garden

345. Reverse Vowels of a String

2 min read

📝 Problem Details

💭What Were My Initial Thoughts?

- create a hashmap with all the vowel characters in both uppper and lower case forms
- two pointer approach similar to the problem isPalindrome where we have nested while loops that move the left and right pointers until we encounter vowels
- perform a swap on the vowels

⌛ Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(1)

💻 Implementation of Solution

class Solution {
public:
    string reverseVowels(string s) {
        // Convert the input string to a character array.
        string word = s;
        int start = 0;
        int end = s.length() - 1;
        string vowels = "aeiouAEIOU";
        
        // Loop until the start pointer is no longer less than the end pointer.
        while (start < end) {
            // Move the start pointer towards the end until it points to a vowel.
            while (start < end && vowels.find(word[start]) == string::npos) {
                start++;
            }
            
            // Move the end pointer towards the start until it points to a vowel.
            while (start < end && vowels.find(word[end]) == string::npos) {
                end--;
            }
            
            // Swap the vowels found at the start and end positions.
            swap(word[start], word[end]);
            
            // Move the pointers towards each other for the next iteration.
            start++;
            end--;
        }
        
        // Return the modified string.
        return word;
    }
};

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