LeetCode - Easy - 345. Reverse Vowels of a String

Topic

• Two Pointers
• String

Description

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

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”.

Analysis

略

Submission

import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;

public class ReverseVowelsOfAString {
    
    

	private static final Set<Character> VOWELS = //
			new HashSet<>(Arrays.asList('A', 'E', 'I', 'O', 'U', 'a', 'e', 'i', 'o', 'u'));

	public String reverseVowels(String s) {
    
    
		if (s == null || s.length() == 0)
			return s;

		char[] array = s.toCharArray();
		int left = 0, right = array.length - 1;

		while (left < right) {
    
    
			while (left < right && !VOWELS.contains(array[left]))
				left++;

			while (left < right && !VOWELS.contains(array[right]))
				right--;

			char temp = array[left];
			array[left++] = array[right];
			array[right--] = temp;
		}

		return new String(array);
	}
}

Test

import static org.junit.Assert.*;
import org.junit.Test;

public class ReverseVowelsOfAStringTest {
    
    

	@Test
	public void test() {
    
    
		ReverseVowelsOfAString obj = new ReverseVowelsOfAString();

		assertEquals("holle", obj.reverseVowels("hello"));
		assertEquals("leotcede", obj.reverseVowels("leetcode"));
	}
}