p345

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LeetCode p345 Reverse Vowels of a String 题解

1.题目：

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”.

题意：

输入一个字符串，将第一个元音字母与最后一个元音字母交换，第二个与倒数第二个交换。。以此类推。

2.解题思路:

两个指针搜索交换。

3.代码

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public class Solution {
    public String reverseVowels(String s) {
       char[] a = { 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U' };
		char[] list = s.toCharArray();

		HashSet<Character> characters = new HashSet<Character>();
		for (char i : a) {
			characters.add(i);
		}

		for (int i = 0, j = list.length - 1; i < j; i++, j--) {
			while (i < j && (!characters.contains(list[i]))) {
				i++;
			}
			while (i < j && (!characters.contains(list[j]))) {
				j--;
			}
			// System.out.println(i+" "+j);
			if (i >= j)
				break;
			char c = list[i];
			list[i] = list[j];
			list[j] = c;
			// System.out.println(new String(list));
		}
		return new String(list);
    }
}

4.一些总结：