[leetcode] Reverse String II

 1 class Solution {
 2     public String reverseStr(String s, int k) {
 3         char[] array = s.toCharArray();
 4         for ( int i = 0 ; i < s.length() ; i +=  2*k ){
 5             reverse(array,i,i+k-1);
 6         }
 7         return String.valueOf(array);
 8     }
 9 
10     private void reverse(char[] array, int start, int end) {
11         if ( start > array.length ) return;
12         int low = start;
13         int high = Math.min(end,array.length-1);
14         while ( low < high ){
15             char c = array[low];
16             array[low] = array[high];
17             array[high] = c;
18             low++;
19             high--;
20         }
21     }
22 }