题目：

代码：

 import java.util.Scanner;

public class ComputeValue {
    
    public static void main(String[] args) {
        int n;
        int[] arr;
        Scanner scan = new Scanner(System.in);
        
        n = scan.nextInt();
        arr = new int[n+1];
        
        for(int i=1;i<=n;i++) {
            arr[i]=scan.nextInt();
        }
        
        cv(arr);
    }
    
    public static void cv(int[] arr) {
        boolean desc=false;
        float MidValue=0;
        
        
        if(arr[1]>arr[arr.length-1]) {
            desc  = true;
            System.out.print(arr[1]+" ");
            }else {
            System.out.print(arr[arr.length-1]+" ");
            }
        
        if((arr.length-1)%2==0) {
            int middle = (arr.length-1)/2;
        
            MidValue = (float)(arr[middle]+arr[middle+1])/2;
        
            if((arr[middle]+arr[middle+1])%2==0)
                System.out.print((int)MidValue+" ");
            else
                System.out.printf("%.1f ",MidValue);
        }else {
            System.out.print(arr[(arr.length-1)/2+1]+" ");
        }
        
        if(desc)
            System.out.print(arr[arr.length-1]);
        else
            System.out.print(arr[1]);
        
    }

}

主类名称改为Main