题解 | #点击消除#

import java.util.*;

// 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);
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String str = in.nextLine();
            Stack<Character> stack = new Stack<>();
            for(int i = 0; i < str.length(); i++){
                char ch = str.charAt(i);
                if(stack.isEmpty() || stack.peek() != ch){
                    stack.push(ch);
                }else {
                    stack.pop();
                }
            }
            //栈当中存储好了数据
            if(stack.empty()){
                System.out.print(0);
            }else{
                Stack<Character> stack2 = new Stack<>();
                while(!stack.empty()){
                    stack2.push(stack.pop());
                }
                while(!stack2.empty()){
                    System.out.print(stack2.pop());
                }

            }
            


        }
    }
}