Maximum Product Subarray.cpp

/*
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.

Example 1:
Input:
N = 5
Arr[] = {6, -3, -10, 0, 2}
Output: 180
Explanation: Subarray with maximum product
is  6, -3, -10 which gives product as 180.

Example 2:
Input:
N = 6
Arr[] = {2, 3, 4, 5, -1, 0}
Output: 120
Explanation: Subarray with maximum product
is 2, 3, 4, 5 which gives product as 120.
Your Task:
You don't need to read input or print anything. Your task is to complete the function maxProduct() which takes the array of integers arr and n as parameters and returns an integer denoting the answer.
Note: Use 64-bit integer data type to avoid overflow.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 <= N <= 500
-102 <= Arri <= 102
*/

long long maxProduct(int *nums, int n)
{
  long long min_here = nums[0], max_here = nums[0], ans = nums[0];

  for (int i = 1; i < n; ++i)
  {
    if (nums[i] < 0)
      swap(max_here, min_here);

    max_here = max((long long)nums[i], max_here * nums[i]);
    min_here = min((long long)nums[i], min_here * nums[i]);

    ans = max(ans, max_here);
  }

  return ans;
}