题解 | 点击消除

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        char[] s = in.next().toCharArray();
        StringBuilder st = new StringBuilder();//StringBuilder此处可以用来模拟栈
        for(int i = 0;i<s.length;i++){//遍历数组
            char ch = s[i];
            if(st.length() != 0 && ch == st.charAt(st.length()-1)){
                //出栈
                st.deleteCharAt(st.length()-1);
            }
            else{
                //进栈
                st.append(ch);
            }
        }
        System.out.println(st.length() == 0 ? 0 : st.toString());
    
    }
}