1913. Maximum Product Difference Between Two Pairs

Easy

The product difference between two pairs (a, b) and (c, d) is defined as (a * b) - (c * d).

• For example, the product difference between (5, 6) and (2, 7) is (5 * 6) - (2 * 7) = 16.

Given an integer array nums, choose four distinct indices w, x, y, and z such that the product difference between pairs (nums[w], nums[x]) and (nums[y], nums[z]) is maximized.

Return the maximum such product difference.

Example 1:

Input: nums = [5,6,2,7,4]
Output:
 34
Explanation:
 We can choose indices 1 and 3 for the first pair (6, 7) and indices 2 and 4 for the second pair (2, 4).
The product difference is (6 * 7) - (2 * 4) = 34.

Example 2:

Input: nums = [4,2,5,9,7,4,8]
Output:
 64
Explanation:
 We can choose indices 3 and 6 for the first pair (9, 8) and indices 1 and 5 for the second pair (2, 4).
The product difference is (9 * 8) - (2 * 4) = 64.

Constraints:

• 4 <= nums.length <= 104

• 1 <= nums[i] <= 104

解題

func maxProductDifference(nums []int) int {
    max, max2, min, min2 := math.MinInt64, math.MinInt64, math.MaxInt64, math.MaxInt64
    
    for _, val := range nums {
        if val>max {
            max2 = max
            max = val
        } else if val>max2 {
            max2 = val
        }
        
        if val<min {
            min2 = min
            min = val
        } else if val<min2 {
            min2 = val
        }
    }
    
    return max*max2 - min*min2
}