alternating chars wip

// Complete the alternate function below.
    static int alternate(String s) {
        String str = removeDuplicates(s);
        if (str.length() < 2) {
            return 0;
        } else {
            boolean[] seen = new boolean[26];
            int bestBet = 0;
            for (int i = 0; i < str.length() - 1; i++) {
                char c1 = str.charAt(i);
                if (seen[(int) c1 - (int) 'a']) {
                    str = removeChar(str, c1);
                    str = removeDuplicates(str);
                    continue;
                }
                for (int j = i + 1; j < str.length(); j++) {
                  char c2 = str.charAt(j);
                  if (seen[(int) c2 - (int) 'a'] || c1 == c2) {
                        str = removeChar(str, c1);
                        str = removeDuplicates(str);
                      continue;
                  }
                  seen[(int) c1 - (int) 'a'] = true;
                  System.out.println(c1 + " " + c2);
                  int candidateLength = 1;
                  char currentChar = c1;
                  for (int k = j; k < str.length(); k++) {
                      if (str.charAt(k) == currentChar) {
                          candidateLength = -1;

                          break;
                      }
                      if (currentChar == c1 && str.charAt(k) == c2
                          || currentChar == c2 && str.charAt(k) == c1) {
                              candidateLength++;

                          currentChar = currentChar == c1 ? c2 : c1;
                          //System.out.println("currentChar " + currentChar);
                      }
                  }
                System.out.println(candidateLength);
                  if (candidateLength >= bestBet) {
                      bestBet = candidateLength;
                  }
                }
            }
            System.out.println(bestBet);
            return bestBet;
        }

    }
    static String removeChar(String str, char cToRemove) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            if (c != cToRemove) {
                sb.append(c);
            }
        }
        return sb.toString();
    }
    static String removeDuplicates(String s) {
        boolean dup = true;
        String str = s;
        while (dup) {
            char cToRemove = '\0';
            dup = false;
            for (int i = 1; i < str.length(); i++) {
                if (str.charAt(i) == str.charAt(i-1)) {
                    dup = true;
                    cToRemove = str.charAt(i);
                    break;
                }
            }
            if (dup) {
                str = removeChar(str, cToRemove);
                System.out.println("remove duplicates result: " + str);

            }
        }
        return str;
    }