◻️345. Reverse Vowels of a String (easy)

Given a string s, reverse only all the vowels in the string and return it.

The vowels are 'a', 'e', 'i', 'o', and 'u', and they can appear in both lower and upper cases, more than once.

Example 1:

Input: s = "hello"
Output: "holle"

Example 2:

Input: s = "leetcode"
Output: "leotcede"

---

Solutions

Normal

Runtime 5 ms Memory 9.35 MB

// Solution taken from leetcode.

class Solution {
public:
    string reverseVowels(string s) {
        int i=0;
        int j=s.length()-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]);
                i++;
                j--;
            }
        }
        return s;
    }
    private:
        bool isVowel(char c){
            c = tolower(c);
            return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
        }
};

Own Solution

Runtime 4 ms Memory 9.34 MB

class Solution {
public:
    string reverseVowels(string s) {
        int back_index=s.length()-1;
        for(int i=0; i<s.length()-1; i++){
            if(back_index <= i){break;}
            else if(s[i]=='a' || s[i]=='e' || s[i]=='i' || s[i]=='o' || s[i]=='u'
            || s[i]=='A' || s[i]=='E' || s[i]=='I' || s[i]=='O' || s[i]=='U'){
                for(int j=back_index; j>i; j--){
                    if(s[j]=='a' || s[j]=='e' || s[j]=='i' || s[j]=='o' || s[j]=='u' || s[j]=='A' || s[j]=='E' || s[j]=='I' || s[j]=='O' || s[j]=='U'){
                        char temp = s[i];
                        s[i] = s[j];
                        s[j] = temp;
                        back_index=j-1;
                        break;
                    }
                }
            }
        }
        return s;
    }
};