پاسخ سوال مساحت محصور کوئرا

import java.util.Stack;
import java.util.Scanner;
 
public class Main
{
 
    static int getMaxArea(int hist[], int n)  
    { 
 
        Stack<Integer> s = new Stack<>(); 
        
        int max_area = 0; 
        int tp; 
        int area_with_top; 
        int i = 0; 
        while (i < n) 
        { 
            if (s.empty() || hist[s.peek()] <= hist[i]) 
                s.push(i++); 
            
            else
            { 
                tp = s.peek();  
                s.pop();  
                
                area_with_top = hist[tp] * (s.empty() ? i : i - s.peek() - 1); 
                
                if (max_area < area_with_top) 
                    max_area = area_with_top; 
            } 
        } 
 
        while (s.empty() == false) 
        { 
            tp = s.peek(); 
            s.pop(); 
            area_with_top = hist[tp] * (s.empty() ? i : i - s.peek() - 1); 
            
            if (max_area < area_with_top) 
                max_area = area_with_top; 
        } 
        
        return max_area; 
        
    } 
    
    public static void main(String[] args)  
    { 
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        int[] arr = new int[n];
        
        for(int i = 0; i < n; i++){
            arr[i] = input.nextInt();
        }
        
        System.out.println(getMaxArea(arr, arr.length)); 
    } 
}