In this Leetcode Reverse Vowels of a String problem solution, you have 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 cases.

Leetcode Reverse Vowels of a String problem solution


Problem solution in Python.

def reverseVowels(self, s):
    """
    :type s: str
    :rtype: str
    """
    
    vowels = "AaEeIiOoUu"
    
    i = 0
    j = len(s) - 1
    
    l = list(s)
    
    while i < j:
        
        if l[i] in vowels and l[j] in vowels:
            l[i], l[j] = l[j], l[i]
            i += 1
            j -= 1
        elif l[i] in vowels:
            j -= 1
        elif l[j] in vowels:
            i += 1
        else:
            i += 1
            j -= 1
    
    return "".join(l)



Problem solution in Java.

public String reverseVowels(String s) {
        int i = 0, j = s.length() - 1;
        char[] sarr = s.toCharArray();
        while(i < j) {
            if(!s.substring(i, i+1).matches("[aeiouAEIOU]")) {
                i++;
            } else if(!s.substring(j, j+1).matches("[aeiouAEIOU]")) {
                j--;
            } else {
                char temp = sarr[i];
                sarr[i] = sarr[j];
                sarr[j] = temp;
                i++;
                j--;
            }
        }
        return new String(sarr);
    }


Problem solution in C++.

class Solution {
public:
    bool isVowel(char x){
        return (x == 'a' || x == 'e' || x == 'i' || x == 'o' || x== 'u' 
                || x == 'A' || x == 'E' || x == 'I' || x == 'O' || x== 'U')?true:false;
    }
    string reverseVowels(string str) {
        int s=0;
        int e=str.length()-1;
        while(s<=e){
            if(!isVowel(str[s]) && isVowel(str[e])){
                s++;
            }
            if(!isVowel(str[e]) && isVowel(str[s])){
                e--;
            }
            if(isVowel(str[s]) && isVowel(str[e])){
                swap(str[s],str[e]);
                s++;
                e--;
            }
            if(!isVowel(str[s]) && !isVowel(str[e])){
                s++;
                e--;
            }
        }
        return str;
    }
};


Problem solution in C.

unsigned char isVowels(char c)
{
    switch(c)
    {
        case 'a':
        case 'o':
        case 'e':
        case 'i':
        case 'u':
        case 'A':
        case 'O':
        case 'E':
        case 'I':
        case 'U':
            return 1;
        default:
            return 0;
    }
    return 0;
}

void swap(char* c1,char* c2)
{
    char tmp = 0;
    tmp = *c1;
    *c1 = *c2;
    *c2 = tmp;
}

char* reverseVowels(char* s) {
    size_t i = 0, j = 0;

    if (NULL == s)
    {
        return s;
    }

    for (i = 0, j = strlen(s); i != j; ++i)
    {
        if (isVowels(*(s+i)))
        {
            while(i != --j)
            {
                if (isVowels(*(s+j)))
                {
                    swap(s+i,s+j);
                    break;
                }
            }
            if (i == j)
            {
                break;
            }
        }
    }
    return s;
}