测试了好几个例子都过了，一直全re，求助！JAVA

import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int N=sc.nextInt();
        int arr[]=new int[100];
        int length=0;
        for(int i=0;i<N*N;i++){
            arr[i]=sc.nextInt();
            if(i%2==0){
                for(int j=1;j<=arr[i];j++){
                    System.out.print("0");
                    length++;
                    if(length==N){
                        System.out.println();
                        length=0;
                    }
                }
            }if(i%2!=0){
                for(int j=1;j<=arr[i];j++){
                    System.out.print("1");
                    length++;
                    if(length==N){
                        System.out.println();
                        length=0;
                    }
                }
            }
        }
    }
}