leetcode 345. Reverse Vowels of a String

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

Example 1:
Given s = "hello", return "holle".

Example 2:
Given s = "leetcode", return "leotcede".

简单的字符操作。

class Solution {
public:
    string reverseVowels(string s) {
        int l=0,r=s.length()-1;
        set<char>st;
        st.insert('a');
        st.insert('e');
        st.insert('i');
        st.insert('o');
        st.insert('u');
        st.insert('A');
        st.insert('E');
        st.insert('I');
        st.insert('O');
        st.insert('U');
        while(l<r){
            if(st.count(s[l])&&st.count(s[r])){
                swap(s[l],s[r]);
                l++;
                r--;
            }
            else if(st.count(s[l])){
                r--;
            }
            else if(st.count(s[r])){
                l++;
            }
            else{
                l++;
                r--;
            }
            
        }
        return s;
    }
};