题解 | #大雨吃小鱼#

import java.util.Scanner;
import java.util.*;
import java.lang.*;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        // while (in.hasNextInt()) { // 注意 while 处理多个 case
        //     int a = in.nextInt();
        //     int b = in.nextInt();
        //     System.out.println(a + b);
        // }
        int n = in.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i ++){
            arr[i] = in.nextInt();
        }
        int[] times = new int[n];
        Deque<Integer> stack = new ArrayDeque<>();
        for (int i = n - 1; i >= 0; i --){
            while (!stack.isEmpty() && arr[stack.peek()] < arr[i]){
                int cur = stack.pop();
                times[i] = Math.max(times[i] + 1, times[cur]);
            }
            stack.push(i);
        }
        // if (stack.isEmpty()){
        //     return 0;
        // }
        int res = 0;
        for (int i : times){
            res = Math.max(res, i);
        }
        
        
        System.out.println(res);
    }
}