[BOJ] 백준 10819 - 차이를최대로 (JAVA)

순열 방식을 swap 해줬습니다.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
 
public class Main10819_차이를최대로{
        static int[] arr;
        static int result;
        static int num =0;
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(br.readLine());
        arr = new int[N];
        StringTokenizer st = new StringTokenizer(br.readLine(), " ");
        for (int i = 0; i < arr.length; i++) {
            arr[i] = Integer.parseInt(st.nextToken());
        }
        
        nPr(0,N);
        System.out.println(num);
        
    }
    
    public static void nPr(int len , int r ) { //순열
        
        if(len == r) {
            result = 0;
            for (int i = 0; i < arr.length-1; i++) {
                result += Math.abs(arr[i+1]- arr[i]);
            }
            if(num<result) {
                num = result;
            }
            return;
            
            
        }
        for (int i = len; i < arr.length; i++) {
            int temp = arr[len];
            arr[len] = arr[i];
            arr[i] = temp;
            nPr(len +1, r);
            
            temp = arr[len];
            arr[len] = arr[i];
            arr[i] = temp;
        }
        
    }
}