Longest Substring with K Distinct Characters

Given a string, find the length of the longest substring in it with no more than K distinct characters.

You can assume that K is less than or equal to the length of the given string.

Example 1:

• Input: String="araaci", K=2
• Output: 4

public int findLength(String str, int k) {
        var maxLength = 0;
        var len = 0;
        var windowStart = 0;
        var charCountMap = new HashMap<Character, Integer>();
        for (var windowEnd = 0; windowEnd < str.length(); windowEnd ++) {
            len ++;
            var endCh = str.charAt(windowEnd);
            charCountMap.put(endCh, charCountMap.getOrDefault(endCh, 0) + 1);
            while (charCountMap.size() > k) {
                var startCh = str.charAt(windowStart);
                if (charCountMap.containsKey(startCh)) {
                    charCountMap.put(startCh, charCountMap.get(startCh) - 1);
                    if (charCountMap.get(startCh) == 0) {
                        charCountMap.remove(startCh);
                    }
                }
                windowStart ++;
                len --;
            }
            maxLength = Math.max(maxLength, len);
        }
        return maxLength;
    }