Leetcode 186 Reverse Words in a String II

Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters.

The input string does not contain leading or trailing spaces and the words are always separated by a single space.

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

Could you do it in-place without allocating extra space?

Solution 1: rotate each word and then rotate the entire Sting.

 public class Solution {  
   public void reverseWords(char[] s) {  
     int i=0, n=s.length;  
     while (i<n){  
       int j=i;  
       while (j<n && s[j]!=' ') j++;  
       reverse(s,i,j-1);  
       i=++j;  
     }  
     reverse(s,0,n-1);  
   }  
   private void reverse(char[] s, int i, int j) {  
     while (i<j){  
       char temp=s[i];  
       s[i++]=s[j];  
       s[j--]=temp;  
     }  
   }  
 }