LeetCode 186. Reverse Words in a String II（反转单词）

原题网址：https://leetcode.com/problems/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?

方法：两次反转。

public class Solution {    private void reverse(char[] s, int from, int to) {        while (from<to) {            char c = s[from];            s[from] = s[to];            s[to] = c;            from ++;            to --;        }    }    public void reverseWords(char[] s) {        int pos = 0;        for(int i=0; i<=s.length; i++) {            if (i<s.length && s[i] != ' ') continue;            reverse(s, pos, i-1);            pos = i+1;        }        reverse(s, 0, s.length-1);    }}