题解 | #点击消除#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayDeque;
import java.util.Deque;
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) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        Deque<Character> stack = new ArrayDeque<>();
        char[]  chars =  br.readLine().toCharArray();
        for (char c : chars) {
            if (!stack.isEmpty() && stack.peek() == c) {
                stack.pop();
            } else {
                stack.push(c);
            }
        }
        StringBuilder sb = new StringBuilder();
        if(stack.isEmpty()){
            System.out.println(0);
        }
        while (!stack.isEmpty()) {
            sb.append(stack.removeLast());
        }
        System.out.println(sb);
    }
}