Maximum Product Subarray

Given an array Arr[] that contains N integers (may be positive, negative or zero). Find the product of the maximum product subarray.

• Time : O(n)
• Space : O(1)

class Solution {
public:
    // Function to find maximum product subarray
    long long maxProduct(vector<int> arr, int n) {
        long long res = LLONG_MIN, first = LLONG_MIN, product = 1;
        for(auto& a : arr) {
            if(!a) {
                if(abs(product) > abs(first)) {
                    res = max(res, product / first);
                }
                res = max(res, 0ll);
                first = LLONG_MIN, product = 1;
            } else {
                product *= a;
                if(first == LLONG_MIN and product < 0) first = product;
                res = max(res, product);
            }
        }
        if(abs(product) > abs(first)) {
            res = max(res, product / first);
        }
        return res;
    }
};