题解 | 点击消除

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.next();
        char[] arr = str.toCharArray();
        StringBuilder s = new StringBuilder();
        for(int i=0;i<str.length();i++){
            if(s.length()!=0&&arr[i]==s.charAt(s.length()-1)){
                //出栈
                s.deleteCharAt(s.length()-1);
            }else{
                //入栈
                s.append(arr[i]);
            }
        }
        System.out.println(s.length()==0?0:s.toString());
    }
}