Acwing 2022年3月20日第一届全国高校联赛 第二题 农田灌溉

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;


public class acwing农田灌溉 {

    static ArrayList list2 = new ArrayList<>();

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int t = scanner.nextInt();

        for (int i = 0; i < t; i++) {
            int n = scanner.nextInt();
            int k = scanner.nextInt();
            int[] arr=new int[k];
            ArrayList list = new ArrayList<>();
            for (int j = 0; j < k; j++) {
                arr[j]= scanner.nextInt();
            }
            ff(n,arr,list);
        }
        for (Integer integer : list2) {
            System.out.println(integer);
        }
    }

    private static void ff(int n, int[] arr, ArrayList list) {
        list.add(arr[0]);
        for (int i = 1; i < arr.length; i++) {
            int tt=arr[i]-arr[i-1];
            list.add(tt / 2 + 1);
        }
        list.add(n-arr[arr.length-1]+1);
        Collections.sort(list);
        int res=list.get(list.size()-1);
        list2.add(res);
    }


}