345-Reverse-Vowels-of-a-String.md

345. Reverse Vowels of a String (Java)

Problem

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".

Solution 1.

這題將母音位置反轉其餘不變，所以用一個會圈分別從頭和尾巴同時一個一個掃，找到母音即可交換位置。

• String 走訪
• Run Time: 17 ms
• 時間複雜度: O(n log n)
• 空間複雜度: O(n)

class Solution {
    public String reverseVowels(String s) {
        String vowels = "aeiouAEIOU";
		char arr[] = s.toCharArray();
		int i = 0, j = s.length() - 1;
		while (i < j) {
			while (i < j && !vowels.contains(arr[i] + "")) {
				i++;
			}
			while (i < j && !vowels.contains(arr[j] + "")) {
				j--;
			}
			char temp = arr[i];
			arr[i] = arr[j];
			arr[j] = temp;
			i++;
			j--;
		}
		return new String(arr);
    }
}