LeetCode345. Reverse Vowels of a String（模拟）

Easy
Accepted：139,692
Submissions：343,552

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

Example 1:

Input: "hello"
Output: "holle"

Example 2:

Input: "leetcode"
Output: "leotcede"

Note:

The vowels does not include the letter "y".

链接

https://leetcode.com/problems/reverse-vowels-of-a-string/

题意

对一个字符串的所有元音字母进行翻转。

题解

直接模拟就好了，使用对撞指针，时间复杂度为$O(n)$，注意一下大小写字母的判断。

代码

Runtime: 8 ms, faster than 98.09% of C++ online submissions for Reverse Vowels of a String.
Memory Usage: 1.3 MB, less than 28.79% of C++ online submissions for Reverse Vowels of a String.

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

The end.
2019年2月4日星期一