【字符串】面试题58 - II. 左旋转字符串

题目：

解答:

思路为三次反转。

 1 class Solution {
 2 public:
 3     int reverse_string(string& s, int start, int end) 
 4     {
 5         for (int i = start; i <= (start + end) / 2; i++) 
 6         {
 7             char temp = s[i];
 8             s[i] = s[start+end-i];
 9             s[start+end-i] = temp;
10         }
11         return 0;
12     }
13 
14     string reverseLeftWords(string s, int n) 
15     {
16         int length = s.length();
17 
18         reverse_string(s, 0, length-1);
19         reverse_string(s, 0, length-n-1);
20         reverse_string(s, length-n, length-1);
21         
22         return s;
23     }
24 };