点击消除 题解

import java.util.*;
import java.math.*;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;
import java.io.OutputStreamWriter;
import java.io.BufferedReader;
import java.io.PrintWriter;
public class Main {
    public static HashMap<Integer,Long>map = new HashMap<>();
    public static void main(String args[])throws IOException {
        StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        in.nextToken();
        String s = in.sval;
        int num[] = new int[s.length()];
        Arrays.fill(num,1);
        int l=0,r=0;
        String s1="";
        for(int i=1;i<s.length();i++)
        {
            if(num[i]!=0&&num[i-1]!=0&&s.charAt(i)==s.charAt(i-1))
            {
                r = i;
                l = i-1;
                while(l>=0&&r<s.length()&&s.charAt(l)==s.charAt(r))
                {
                num[l] = 0;
                num[r] = 0;
                    l--;r++;
                while(l>=0&&num[l]==0)
                    l--;
                while(r<s.length()&&num[r]==0)
                    r++;
                }
                 
            }
        }
        for(int i=0;i<s.length();i++)
        {
            if(num[i]!=0)
                s1+=s.charAt(i);
        }
        if(s1.length()==0)
            out.print(0);
        else{
            out.print(s1);
        }
        out.flush();
    }
}