leetcode-reverse words in a string

问题来源：https://oj.leetcode.com/problems/reverse-words-in-a-string/

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

For example,
Given s = "the sky is blue",
return "blue is sky the".

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.
• 我的实现代码：（开始看错了题目要求，以为就是一个字符串反转，直接用了new StringBuffer(s).reverse().toString()，后来发现不是一个简单的所有字符反转，而是单词顺序反转，但是单词还是那个单词！）

[java] view plaincopy

1. public class Solution {  
2.     public String reverseWords(String s) {  
3.         int length = s.length();  
4.         StringBuffer buff = new StringBuffer();  
5.         StringBuffer sb = new StringBuffer();  
6.         for (int i = length; i > 0; i--) {  
7.               
8.             if (s.charAt(i - 1) == ' ') {  
9.                 buff.append(sb.reverse().toString());  
10.                 sb = new StringBuffer();  
11.                 buff.append(' ');  
12.                 while (i-1 > 0) {  
13.                     if (s.charAt(i - 2) == ' ') {  
14.                         i--;  
15.                     } else  
16.                         break;  
17.                 }  
18.             } else {  
19.                 sb.append(s.charAt(i-1));  
20.             }  
21.         }  
22.         buff.append(sb.reverse().toString());  
23.         return buff.toString().trim();  
24.     }  
25.   
26.     public static void main(String[] args) {  
27.         Scanner scan = new Scanner(System.in);  
28.         String s = scan.nextLine();  
29.         System.out.println(new Solution().reverseWords(s));  
30.   
31.     }  
32.   
33. }