HackerEarth Thief and Warehouses problem solution

In this HackerEarth Thief and Warehouses problem solution There are N warehouses. The warehouses are located in a straight line and are indexed from 1 to N. Each warehouse contains some number of sacks.

A thief decides to rob these warehouses. Thief figured out that he can escape the police if and only if he follows both the following 2 constraints:

1. He will rob only one continuous segment of warehouses.
2. He will rob a same number of sacks from each warehouse.

The thief wants to calculate the maximum number of sacks he can steal without getting caught by the police.

#include<bits/stdc++.h>

#define ll long long
using namespace std;
stack<ll> s;
int main()
{
    int testCases;
    cin>>testCases;
    while(testCases--){
        int n,i;
        scanf("%d",&n);
        ll a[n];
        for(i=0;i<n;i++)
            scanf("%lld",&a[i]);
        ll marea=0,area=0;
        for(i=0;i<n;){
            if(s.empty()||a[s.top()]<=a[i])
                s.push(i++);
            else{
                int tp=s.top();
                s.pop();
                if(s.empty())
                    area=a[tp]*i;
                else
                    area=a[tp]*(i-s.top()-1);
                if(area>marea)
                    marea=area;
            }
        }
        while(!s.empty()){
            int tp=s.top();
                s.pop();
                if(s.empty())
                    area=a[tp]*i;
                else
                    area=a[tp]*(i-s.top()-1);
                if(area>marea)
                    marea=area;
        }
        printf("%lldn",marea);
    }
}