亲们，请帮我看看第一题哪错了？ public static void main(String[] args) { Scanner sc=new Scanner(System.in); String nn=sc.nextLine(); if(nn==null||nn.length()==0){ System.out.println(0); } int n=new Integer(nn); if(n==0||n<4||n%2!=0) System.out.println(0); String str=sc.nextLine(); String[] strings=str.split(" "); int[] arr=new int[strings.length]; for(int i=0;i<strings.length;i++){ arr[i]=new Integer(strings[i]); } Arrays.sort(arr); int max=arr[0]+arr[n-1]; int min=arr[n/2-1]+arr[n/2]; System.out.println(max-min); }