[백준] 2675번 문자열 반복

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
    	
    	Scanner kb = new Scanner(System.in);
    	int T = kb.nextInt();
    	StringBuilder sb = new StringBuilder();
    	
    	for(int i=0; i<T; i++) {
    		int R = kb.nextInt();
    		String a = kb.next();
    		
    		for(int j=0; j<a.length(); j++) {
    			for(int k=0; k<R; k++) {
    				sb.append(a.charAt(j));
    			}
    		}
    		sb.append('\n');
    	}
    	
    	System.out.println(sb.toString());

    }
}