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maxRepeatLetterCount keeps track of the GLOBAL maximum, not LOCAL maximum

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public static int findLength(String str, int k) {

// Note: We're keeping track of GLOBAL max, NOT LOCAL max
Map<Character, Integer> hm = new HashMap<>();
int s = 0, globalMaxFreq = 0, maxLength = 0;

for(int e = 0; e < str.length(); e++)
{
  // Note: hm correctly keeps track of the char frequencies from s -> e
  hm.put(str.charAt(e), hm.getOrDefault(str.charAt(e), 0) + 1);

  // Notice if globalMaxFreq increases, it means the repeating characters are denser
  // in this window than the last, and therefore this will be the new longest window
  // (Note: maxLength = globalMaxFreq + k, when str.length is long enough of couse)
  globalMaxFreq = Math.max(globalMaxFreq, hm.get(str.charAt(e)));

  // That fact will be reflected here, since this if condition will not be met,
  // even if it is met last iteration
  if (e - s + 1 > globalMaxFreq + k)
  {
    hm.put(str.charAt(s), hm.get(str.charAt(s) - 1));
    s++;
  }

  // and maxLength will be updated accordingly
  maxLength = e - s + 1;
}

return maxLength;

}