동적 할당 없이 씨나 씨플플로 했을 때는 통과과 되는 거 같구요 ㅠㅠ

무슨 문제일까요?

import java.math.BigInteger;
import java.util.Scanner;

public class Main { //2193
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt(); //lee chin soo
        
        //1
        //10
        //100 101
        //1000 1001 1010 
        //10000 10001 10010 10100 10101 --> fibonacci?
        //100000 100001 100010 100100 100101 101000 101001 101010 
        System.out.println(pinaryNumber(n));
    }
    public static BigInteger pinaryNumber(int n){
    /*if(n==1 || n==2) return 1;
    else return pinaryNumber(n-1) + pinaryNumber(n-2);*/
    BigInteger[] array = new BigInteger[n+1];
    array[1] =BigInteger.valueOf(1); array[2]=BigInteger.valueOf(1);
    int i =3;
    while(i<=n){
    array[i] = array[i-1].add(array[i-2]);
    //System.out.println("array "+ i +" :: " + array[i]);
    i++;
    }
    return array[n];
    }
}