三月18号360测评剪气球，只能通过69%，求大神指导下

import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner cin = new Scanner(System.in);
		
			int len=cin.nextInt();
			int[] arr=new int[len];
			for(int i=0;i<len;++i){
				arr[i]=cin.nextInt();
			}
			System.out.println(solution(arr));
		cin.close();
	}
	
	public static int solution(int[] arr){
		int sum=1;
		int len=arr.length;
		int startIndex=0;
		for(int i=1;i!=len;){
			while(i!=len && arr[i]!=arr[i-1]){
				i++;
			}
			sum *=subArrMethod(i-startIndex);
			while(i!=len && arr[i]==arr[i-1]){
				i++;
			}
			startIndex=i-1;
		}
		return sum;
	}
	
	public static int subArrMethod(int n){
		return (int)Math.pow(2, n-1);
	}
}