[LC] 82. Remove Adjacent Repeated Characters IV

public class Solution {
  public String deDup(String input) {
    // Write your solution here
    char[] charArr = input.toCharArray();
    LinkedList<Character> stack = new LinkedList<>();
    for (int i = 0; i < charArr.length; i++) {
      char cur = charArr[i];
      if (!stack.isEmpty() && stack.peekFirst() == cur) {
        while (i + 1 < charArr.length && charArr[i] == charArr[i + 1]) {
          i += 1;
        }
        stack.pollFirst();
      } else {
        stack.offerFirst(cur);
      }
    }
    char[] res = new char[stack.size()];
    for (int i = res.length - 1; i >= 0; i--) {
      res[i] = stack.pollFirst();
    }
    return new String(res);
  }
}