Maximum Product of Two Elements in an Array

Problem

Given the array of integers nums, you will choose two different indices i and j of that array. Return the maximum value of (nums[i]-1)*(nums[j]-1). Example 1:

Input: nums = [3,4,5,2]
Output: 12 
Explanation: If you choose the indices i=1 and j=2 (indexed from 0), you will get the maximum value, that is, (nums[1]-1)*(nums[2]-1) = (4-1)*(5-1) = 3*4 = 12.

Example 2:

Input: nums = [1,5,4,5]
Output: 16
Explanation: Choosing the indices i=1 and j=3 (indexed from 0), you will get the maximum value of (5-1)*(5-1) = 16.

Example 3:

Input: nums = [3,7]
Output: 12

Constraints:

2 <= nums.length <= 500
1 <= nums[i] <= 10^3

Solution (Java)

class Solution {
    public int maxProduct(int[] nums) {
        if (nums == null) {
            return 0;
        }

        int first = Integer.MIN_VALUE;
        int second = Integer.MIN_VALUE;
        for (int num : nums) {
            if (num >= first) {
                second = first;
                first = num;
            } else if (num >= second) {
                second = num;
            }
        }
        return (first - 1) * (second - 1);
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).