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?

 

先把每个词反转一遍， 再把整个string 反转一遍。

 1 public class Solution {

 2     public void reverseWords(char[] s) {

 3         for(int i = 0, j = 0; j <= s.length && i < s.length; j ++){

 4             if(j == s.length || s[j] == ' '){

 5                 reverse(s, i, j - 1);

 6                 i = j + 1;

 7             }

 8         }

 9         reverse(s, 0, s.length - 1);

10     }

11     

12     private void reverse(char[] c, int s, int e){

13         while(s < e){

14             char tmp = c[s];

15             c[s] = c[e];

16             c[e] = tmp;

17             s ++; e --;

18         }

19     }

20 }