Maximum Product Subarray

/*
Explanation:
Need to track both max and min as two large negative numbers would make a large positive number. So track curr_min, curr_max, prev_min, prev_max.
*/

class Solution {
    public int maxProduct(int[] nums) {
        int curr_max, curr_min, prev_max, prev_min, res;
        curr_max = curr_min = prev_max = prev_min = res = nums[0];

        for (int i = 1; i < nums.length; i++) {
            curr_max = Math.max(Math.max(nums[i], prev_max*nums[i]), prev_min*nums[i]);
            curr_min = Math.min(Math.min(nums[i], prev_max*nums[i]), prev_min*nums[i]);

            res = Math.max(curr_max, res);

            prev_max = curr_max;
            prev_min = curr_min;
        }

        return res;
    }
}