문자열 폭발

Stack.get은 처음써본다. 매우 유용하다 https://loosie.tistory.com/317

import java.io.*;
import java.util.*;
class Main{
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
       //stack?
       String s = br.readLine();
       String regex = br.readLine();
       int regexLength = regex.length();

       Stack<Character> stack = new Stack<>();

       for(int i=0 ; i<s.length() ; i++){
        stack.push(s.charAt(i));

        if(stack.size() >= regexLength){
            boolean flag = true;
            for(int j=0 ; j<regexLength; j++){
                if(stack.get( (stack.size() - regexLength) + j) != regex.charAt(j)){
                    flag = false;
                    break;
                }
            }
            if(flag){
                for(int j=0 ; j<regexLength ; j++){
                    stack.pop();
                }
            }
        }
       }
       StringBuilder sb = new StringBuilder();
       for(char c : stack){
        sb.append(c);
       }
       System.out.print(sb.length()==0 ? "FRULA" : sb.toString()  );
        
    }
}