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leetcode1913: Maximum Product Difference Between Two Pairs #306

Open carloscn opened 1 year ago

carloscn commented 1 year ago

Description

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

carloscn commented 1 year ago

Analysis

pub fn max_product_difference(nums: Vec<i32>) -> i32
{
    if nums.len() < 4 {
        return 0;
    }

    let mut ret:i32 = 0;

    let (mut first_max, mut sec_max, mut first_min, mut sec_min) =
        (i32::MIN, i32::MIN + 1, i32::MAX, i32::MAX - 1);

    for i in 0..nums.len() {
        if nums[i] > first_max {
            sec_max = first_max;
            first_max = nums[i];
        } else if nums[i] <= first_max && nums[i] > sec_max {
            sec_max = nums[i];
        }

        if nums[i] < first_min {
            sec_min = first_min;
            first_min = nums[i];
        } else if nums[i] >= first_min && nums[i] < sec_min {
            sec_min = nums[i];
        }
    }

    ret = (first_max * sec_max) - (first_min * sec_min);

    return ret;
}
carloscn commented 1 year ago

Code

https://review.gerrithub.io/c/carloscn/structstudy/+/1167486 https://github.com/carloscn/structstudy/commit/9952d08cbafe7b36ee1df1c45b4806cb92a20555