目录 
题目
Write a function that takes a string as input and reverse only the vowels of a string.
Example:
Given s = “hello”, return “holle”.
Given s = “leetcode”, return “leotcede”.
Note:
The vowels does not include the letter “y”.
解决方案
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| public class Solution {
public String reverseVowels(String s) {
int N = s.length();
if(s == null || N == 0) return "";
StringBuilder builderVowel = new StringBuilder();
for(int i = 0; i < N; i++){
if(isVowel(s.charAt(i))){
builderVowel.append(s.charAt(i));
}
}
int k = builderVowel.length()-1;
StringBuilder builder = new StringBuilder();
for(int i = 0; i < N; i++){
if(!isVowel(s.charAt(i))){
builder.append(s.charAt(i));
} else {
builder.append(builderVowel.charAt(k));
k--;
}
}
return builder.toString();
}
private static boolean isVowel(char input){
if('a' == input || 'e' == input || 'i' == input || 'o' == input || 'u' == input ||
'A' == input || 'E' == input || 'I' == input || 'O' == input || 'U' == input){
return true;
} else {
return false;
}
}
}
|
注意事项
- 元音字母为a,e,i,o,u，同时要考虑到大写。
- 第一次遍历找到所有元音字母并按顺序保存到一个builderVowel中。第二次遍历，如果当前为不是原因，直接添加到结果builder中，如果当前位是元音字母，则从builderVowel尾部取出一个字符添加到builder中。
