541. Reverse String II

 1 static int wing=[]()
 2 {
 3     std::ios::sync_with_stdio(false);
 4     cin.tie(NULL);
 5     return 0;
 6 }();
 7 
 8 class Solution 
 9 {
10 public:
11     string reverseStr(string s, int k) 
12     {
13         int len=s.length();
14         auto p=s.begin();
15         int i;
16         for(i=k;i<=len;i+=2*k)
17             reverse(p+i-k,p+i);
18         i-=2*k;
19         if(len==i)
20             return s;
21         else if(len-i>k)
22             reverse(p+i+k,s.end());
23         return s;
24     }
25 };