leetcode151.翻转字符串里的单词

 1 class Solution {
 2 public:
 3     void reverseChar(string& s, int start, int end)
 4     {
 5         char tmp;
 6         while(start < end) {
 7             tmp = s[start];
 8             s[start] = s[end];
 9             s[end] = tmp;
10             start++;
11             end--;
12         }
13     }
14 
15     void deleteSpace(string& s) {
16         int len = s.size();
17         int i = 0, j = 0;
18         
19         while(j < len && s[j] == ‘ ‘) ++j; //跳过头部空格
20 
21         while(j < len) {
22             while(j < len && s[j] != ‘ ‘) s[i++] = s[j++];
23             while(j < len && s[j] == ‘ ‘) ++j;
24             if(j < len) s[i++] = ‘ ‘; //如果不是最后一个单词 则加一个空格
25         }
26         s = s.substr(0, i);
27     }
28 
29     string reverseWords(string s) {
30         reverse(s.begin(), s.end());
31         int ps = 0, pe = 0;
32         while(s[ps]) {
33             while(s[ps] == ‘ ‘) ++ps; //找到单词的开头
34 
35             pe = ps;
36 
37             while(s[ps] != ‘ ‘ && s[ps]) ++ps; //找到单词结尾
38 
39             reverseChar(s, pe, ps-1);
40         } 
41         deleteSpace(s);
42         return s;
43     }
44 };