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".

思路: 用一个hash表存一下元音字符, 然后设置左右指针找到两个都是元音的位置交换一下就可以了. 注意字符是大小写都有的.

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