剑指offer——67左旋转字符串

 1 class Solution02 {
 2 public:
 3     string LeftRotateString(string str, int n) {
 4         int size = str.length();
 5         if (size < 2 || n % size == 0)return str;
 6         n %= size;
 7         Reverse(str, 0, n - 1);
 8         Reverse(str, n, size - 1);
 9         Reverse(str, 0, size - 1);
10         return str;
11     }
12 private:
13     void Reverse(string &str,int L, int R)
14     {
15         while (L < R) {
16             swap(str[L], str[R]);
17             ++L, --R;
18         }
19     }
20 };