Codeforces Vanya and Lanterns

import java.text.DecimalFormat;import java.util.Arrays;import java.util.Scanner;public class VanyaAndLanterns {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = scanner.nextInt();int l = scanner.nextInt();int[] a = new int[n];for(int i = 0; i < n; i++) {a[i] = scanner.nextInt();}Arrays.sort(a);//求直径int r = Math.max(a[0], l- a[n-1]) * 2;for (int i = 0; i < n-1; i++) {r = Math.max(r, a[i+1] - a[i]);}DecimalFormat decimalFormat = new DecimalFormat("0.0000000000");System.out.println(decimalFormat.format(r / 2.0));}}