题解 | #点击消除#

import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
    public static void main(String[] args) throws IOException {
        //点击消除
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String s = br.readLine();
        StringBuilder sb = new StringBuilder(s.length());
        int j=-1;
        for (int i = 0; i < s.length(); i++) {
            //与栈顶元素不相等则入栈
            if(j==-1 || sb.charAt(j)!=s.charAt(i)){
                sb.append(s.charAt(i));
                j++;
            }else {//否则出栈
                sb.deleteCharAt(j--);
            }
        }
        System.out.println(sb.length()!=0?sb.toString():0);
    }
}