lengthOfLongestSubstringKDistinct

public int lengthOfLongestSubstringKDistinct(String str, int k) {
        int maxLength = 0;
        int distinct = 0;
        int[] charCounts = new int[256];
        for (int left = 0, right = 0; right < str.length(); right++) {
            char rightChar = str.charAt(right);
            if (charCounts[rightChar] == 0) {
                distinct++;
            }
            charCounts[rightChar]++;

            while (distinct > k) {
                char leftChar = str.charAt(left);
                charCounts[leftChar]--;
                if (charCounts[leftChar] == 0) {
                    distinct--;
                }
                left++;
            }

            maxLength = Math.max(maxLength, right - left + 1);
        }
        return maxLength;
    }
    
    public int lengthOfLongestSubstringKDistinct2(String str, int k) {
        int maxLength = 0;
        Map<Character, Integer> charCounts = new HashMap<>();
        for (int left=0, right=0; right < str.length(); right++) {
            char rightChar = str.charAt(right);
            charCounts.put(rightChar, charCounts.getOrDefault(rightChar, 0) + 1);

            while (charCounts.size() > k) {
                char leftChar = str.charAt(left);
                charCounts.put(leftChar, charCounts.get(leftChar) - 1);
                if (charCounts.get(leftChar) == 0) {
                    charCounts.remove(leftChar);
                }
                left++;
            }

            maxLength = Math.max(maxLength, right - left + 1);
        }
        return maxLength;
    }