#1047删除字符串中的所有相邻重复项

final class Solution {
    public String removeDuplicates(String s) {
        StringBuilder stack = new StringBuilder(s.length());
        for (int i = 0; i < s.length(); i++) {
            char current = s.charAt(i);
            int size = stack.length();
            if (size > 0 && stack.charAt(size - 1) == current) {
                stack.setLength(size - 1);
            } else {
                stack.append(current);
            }
        }
        return stack.toString();
    }
}