1406번 에디터

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Stack;
import java.util.StringTokenizer;


public class Main {
	static Stack<Character> leftStack=new Stack<Character> ();
	static Stack<Character> rightStack=new Stack<Character> ();
	public static void main(String[] args) {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(System.out));
		try {
			String startStr=br.readLine();
			for(int j=0;j<startStr.length();j++){
				leftStack.push(startStr.charAt(j));
			}
			String tempCnt=br.readLine();
			int testCase=Integer.parseInt(tempCnt);
			for(int i=0;i<testCase;i++){
				String tempCommand=br.readLine();
				StringTokenizer st=new StringTokenizer(tempCommand);
				while(st.hasMoreElements()){
					String commandStr=(String)st.nextElement();
					if("P".equals(commandStr)){
						String  pStr=(String)st.nextElement();
						leftStack.push(pStr.charAt(0));
					}else if("L".equals(commandStr)){
						if(leftStack.size()>0){
							Character leftTempChar=leftStack.pop();
							rightStack.push(leftTempChar);
						}
					}else if("D".equals(commandStr)){
						if(rightStack.size()>0){
							Character rightTempChar=rightStack.pop();
							leftStack.push(rightTempChar );
						}
					}else if("B".equals(commandStr)){
						if(leftStack.size()>0){
							leftStack.pop();
						}
					}
				}
			}
			StringBuffer lsf=new StringBuffer();
			StringBuffer rsf=new StringBuffer();
			for (Character lchar : leftStack) {
				lsf.append(lchar.toString());
			}
			for (Character rchar : rightStack) {
				rsf.append(rchar.toString());
			}
			bw.write(lsf.toString()+rsf.reverse().toString());
			bw.flush();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			if(br!=null){
				try {
					br.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(bw!=null){
				try {
					bw.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}	
		}
	}
}