deeheem

  public int lengthOfLongestSubStringAtMostKDistinct(String s, int k) {
    int n = s.length();
    int[] count = new int[256];
    int i = 0, numDistinct = 0, ans = 0;

    for (int j = 1; j < s.length(); j++) {
      if (count[s.charAt(j)] == 0) {
        numDistinct++;
      }
      count[s.charAt(j)]++;

deeheem

    public int lengthOfLongestSubStringKDistinct(String s) {
        int n = s.length();
        int[] count = new int[256];
        int i = 0, numDistinct = 0, ans = 0;

        for (int j = 1; j < s.length(); j++) {
            if (count[s.charAt(j)] == 0) {
                numDistinct++;
            }
            count[s.charAt(j)]++;

deeheem

    public int lengthOfLongestSubStringTwoDistinct(String s) {
        int n = s.length();
        int i = 0, j = -1, ans = 0;

        for (int k = 1; k < s.length(); k++) {
            if (s.charAt(k) == s.charAt(k - 1)) {
                continue;
            }
            if (j >= 0 && s.charAt(j) != s.charAt(k)) {
                ans = Math.max(ans, k - i);

deeheem

  public int lengthOfLongestSubString(String s) {
    int n = s.length();
    Set<Character> set = new HashSet<>();
    int ans = 0, i = 0, j = 0;
    while (i < n && j < n) {
      if (!set.contains(s.charAt(j))) {
        set.add(s.charAt(j));
        j++;
        ans = Math.max(ans, j - i);
      } else {