345. Reverse Vowels of a String

345. Reverse Vowels of a String (Easy)

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

Example 1:

Input: "hello"
Output: "holle"

Example 2:

Input: "leetcode"
Output: "leotcede"

Note:
The vowels does not include the letter "y".

 

Companies:
Google

Related Topics:
Two Pointers, String

Similar Questions:

• Reverse String (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/reverse-vowels-of-a-string/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
private:
    bool isVowel(char c) {
        c = tolower(c);
        return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
    }
public:
    string reverseVowels(string s) {
        int i = 0, j = s.size() - 1;
        while (i < j) {
            while (i < j && !isVowel(s[i])) ++i;
            while (i < j && !isVowel(s[j])) --j;
            if (i < j) swap(s[i++], s[j--]);
        }
        return s;
    }
};