写法一

import java.io.*;
import java.util.*;

class Main{
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] f = new int[N];
        for(int i = 0; i < N; ++i){
            f[i] = sc.nextInt();
        }
        Arrays.sort(f);
        long res = 0L;
        for(int i = 0; i < N; ++i){
            res += Math.abs(f[i] - f[i/2]);
        }
        System.out.println(res);
    }
}

写法二

import java.io.*;
import java.util.*;

class Main{
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] f = new int[N];
        for(int i = 0; i < N; ++i){
            f[i] = sc.nextInt();
        }
        Arrays.sort(f);
        long res = 0L;
        for(int i = 0; i < N; ++i){
            res += Math.abs(f[i] - f[N/2]);
        }
        System.out.println(res);
    }
}