leetcode 151. 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".

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

思路：先翻转单个单词，然后再翻转整个句子

class Solution {public:    // 翻转每个字母的函数    void reverseword(string &s, int i, int j){        while(i<j){          char t=s[i];          s[i++]=s[j];          s[j--]=t;        }     }        void reverseWords(string &s) {                int i=0, j=0,l=0,wordcount=0;        int len=s.length();                while(true){            while(i<len && s[i] == ' ') i++;  // 跳过单词前的空格            if(i==len) break;            if(wordcount) s[j++]=' ';            l=j;            while(i<len && s[i] != ' ') {s[j]=s[i]; j++; i++;}             reverseword(s,l,j-1);                // 翻转单词            wordcount++;                    }                s.resize(j);                                   reverseword(s,0,j-1);                  // 翻转整个句子    }};