Next Greater Element using Stack in C++

#include <bits/stdc++.h>

using namespace std;

void PrintNge(int arr[], int n) {
    stack<int> s;
    int res[n];
    // start from the back
    for (int i = n - 1; i >= 0; i--) {
        // remove the top element if it's less than the current element
        if (!s.empty()) {
            while (!s.empty() && s.top() <= arr[i]) {
                s.pop();
            }
        }
        // store the next greater element for the current element being iterated upon
        res[i] = s.empty() ? -1 : s.top();
        // push the current element in the stack
        s.push(arr[i]);
    }
    for (int i = 0; i < n; i++) {
        cout << arr[i] << " --> " << res[i] << endl;
    }
}

int main() {
    int n;
    cin >> n;
    int arr[n];
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
    }
    PrintNge(arr, n);
    return 0;
}