541. Reverse String II

Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.

class Solution {
    public String reverseStr(String s, int k) {
        StringBuilder sb = new StringBuilder (s);
        int len =  s.length();
        int count = len/(2*k);
        int remain = len%(2*k);
         if(count>0)
         {
              for(int i = 0 ;i