345. Reverse Vowels of a String【easy】

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

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

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

 解法一：

class Solution {
public:
    bool isVowels(char x) 
    {
        if (x >= 'A' && x <= 'Z') {
            x += 32;
        }
        return (x == 'a' || x == 'e' || x == 'i' || x == 'o' || x == 'u'); 
    }
    
    void reverseChar(string &s, int start, int end)
    {
        char temp = s[start];
        s[start] = s[end];
        s[end] = temp;
    }
    
    string reverseVowels(string s) {
        int start = 0;
        int end = s.length() - 1;
        
        while (start < end) {
            while (start < end && !isVowels(s[start])) {
                ++start;
            }
            
            while (start < end && !isVowels(s[end])) {
                --end;
            }
            
            reverseChar(s, start, end);
            ++start;
            --end;
        }
        
        return s;
    }
};

注意循环的条件

 

解法二：

class Solution {
public:
    string reverseVowels(string s) {
        int i = 0, j = s.size() - 1;
        while (i < j) {
            i = s.find_first_of("aeiouAEIOU", i);
            j = s.find_last_of("aeiouAEIOU", j);
            if (i < j) {
                swap(s[i++], s[j--]);
            }
        }
        return s;
    }
};

参考@tedbear 的代码。