思路：就是模拟杀手杀人的过程，新开一个数组用于标记被杀死的位置。然后生成新的数组，直到平安夜来临。

public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        while (in.hasNext()) {            int n = in.nextInt();            int[] arr = new int[n];            for (int i = 0; i < n; i++) {                arr[i] = in.nextInt();            }            boolean flag = true;            int res = 0;            while (flag) {                int died =0;                int[] kill = new int[arr.length];                //标记已经被杀死的位置                for (int i = 0; i < arr.length-1; i++) {                    if(arr[i]>arr[i+1]){                        kill[i + 1] = 1;                        died++;                    }                }                //死亡人数是0->今夜是平安夜                if(died==0){                    System.out.println(res);                    break;                }                //清除尸体                for (int i = 0; i < arr.length; i++) {                    if (kill[i] == 1) {                        arr[i] = 0;                    }                }                //生成新数组                res++;                int newlen = arr.length - died;                int[] lived = new int[newlen];                int index = 0;                for (int i = 0; i < n; i++) {                    if (arr[i] != 0) {                        lived[index++] = arr[i];                    }                    if(index==newlen) break;                }                arr = lived;            }        }    }}