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ReverseVowels.java
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ReverseVowels.java
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/*
* Copyright [2017] [Haibo(Tristan) Yan]
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.haibo.yan.algorithm.array;
/**
*
* see 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:
* Given s = "hello", return "holle".
* Example 2:
* Given s = "leetcode", return "leotcede".
*/
public class ReverseVowels {
public String reverseVowels(String s) {
if (null == s) {
return s;
}
char[] cs = s.toCharArray();
int left = 0, right = cs.length - 1;
while (left < right) {
while (left < cs.length && !isVowel(cs[left])) {
left++;
}
while (right >= 0 && !isVowel(cs[right])) {
right--;
}
if (left < right) {
char t = cs[left];
cs[left] = cs[right];
cs[right] = t;
}
left++;
right--;
}
return new String(cs);
}
private boolean isVowel(char c) {
char c1 = (c < 91) ? (char)(c + 32) : c;
return c1 == 'a' || c1 == 'e' || c1 == 'i' || c1 == 'o' || c1 == 'u';
}
}