Reverse Words in a String——LeetCode

Given an input string, reverse the string word by word.

For example,
Given s = "

the sky is blue

",
return "

blue is sky the

".

Update (2015-02-12):
For C programmers: Try to solve it in-place in O(1) space.

click to show clarification.

Clarification:

What constitutes a word?
A sequence of non-space characters constitutes a word.

Could the input string contain leading or trailing spaces?
Yes. However, your reversed string should not contain leading or trailing spaces.

How about multiple spaces between two words?
Reduce them to a single space in the reversed string.

题目大意：给一个String，以空格分隔，以单词为单位反转这个String。

解题思路：用java自带的split，拆成数组，然后组合。。。

public String reverseWords(String s) {
if (s == null || s.length() == 0) {
return s;
}
String[] res = s.split(" ");
if (res.length == 0) {
return "";
}
StringBuilder sb = new StringBuilder();
for (int i = res.length - 1; i >= 0; i--) {
if ("".equals(res[i])) {
continue;
}
sb.append(res[i]).append(" ");
}
return sb.substring(0, sb.length() - 1);
}