Longest Substring with K distinct characters Optimized

import java.util.*;

class LongestSubstringKDistinct {
  public static int findLength(String str, int k) {
    // TODO: Write your code here
    // map to store count.
    Map<Character, Integer> map = new HashMap<>();
    int maxLength = 0;
    int windowStart = 0;
    for(int windowEnd = 0; windowEnd < str.length(); windowEnd++) {
      char rightChar = str.charAt(windowEnd);
      // store character count in map
      map.put(rightChar, map.getOrDefault(rightChar, 0)+1);
      // compare mapsize with k and loop till mapsize less than or equal to k
      while(map.size() > k) {
        // shrink by examining right character.
        char leftChar = str.charAt(windowStart);
        // reduce leftChar len and remove if len is 0
        map.put(leftChar, map.get(leftChar)-1);
        if(map.get(leftChar) == 0) {
          map.remove(leftChar);
        }
        // slide to right.
        windowStart++;
      }

      maxLength = Math.max(maxLength, windowEnd-windowStart + 1);
    }
    return maxLength;
  }
}