9. Maximum Product Subarray

Given an integer array nums, find a that has the largest product, and return the product.
The test cases are generated so that the answer will fit in a 32-bit integer.

Example 1:
Input: nums = [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.

Example 2:

Input: nums = [-2,0,-1]
Output: 0
Explanation: The result cannot be 2, because [-2,-1] is not a subarray.

Constraints:

• 1 <= nums.length <= 2 * 104
• -10 <= nums[i] <= 10
• The product of any subarray of nums is guaranteed to fit in a 32-bit integer.

Approach

• Use prefix and suffix product, the way it moves from both side it seems to ensure to cover all subarrays
• If we encounter a zero then set prefix and suffix as 1

class Solution {
    public int maxProduct(int[] nums) {
        int p = 1, s = 1;
        int m = Integer.MIN_VALUE;
        for (int i = 0; i < nums.length; i++) {
            if (p == 0) p = 1;
            if (s == 0) s = 1;
            p *= nums[i];
            s *= nums[nums.length - i - 1];
            m = Math.max(m, Math.max(p,s));
        }
        return m;
    }
}